Planted Tank Maintenance

Last update: October 17, 1998


Glass Cleaning 
Gravel Vacuuming 
pH Electrodes 
Plant Pruning 
Water Changes 
Water Testing


Depending on your climate, evaporation may or may not be a big concern. In our climate, our large aquariums lose between 1/2 and 1 gallon of water per day! This is a problem for us because of the trickle filters. With the surface skimmer, the water level in the tank remains constant and any differences in water volume are seen in the trickle filter sump. We have markings in the sump that indicate "full" and "needs water". If the water level goes below "needs water", a vortex (mini-tornado) will form by the pump outlet and the pump will suck air.

It is important to note that only water leaves the tank by evaporation -- any salts (like calcium), chemicals and pollutants (metabolites, toxins, etc.) will stay behind. Thus, it is necessary to replenish lost water with RO or distilled water, if possible. If your tap water is very soft and pure, that is acceptable also. If you replenish evaporation with hard water, you will be increasing hardness (or pollution if your tap water is bad) over time.

If you design an automated water top-off system, keep in mind the consequences of what you use for a water source. Also, keep in mind where you need to measure the water level (for exmaple, in the sump if you have a trickle filter).


Fertilization is critical to a planted tank unless you are lucky enough to have “perfect” tap water. Urban tap water is specially treated to remove most trace elements since they are considered contaminants. It is also treated to remove CO2 and to create a pH high enough to prevent corrosion in water pipes. Because of this, we need to use fertilizers and adjust pH to reestablish a suitable environment for plants and fish.

We favor Dupla products since we believe they are well researched and have stringent quality control. Other folks have had success with a home-made solution known as "Poor Man's Dosing Drops" (PMDD). This is a method based on original work by Conlin and Sears and has been discussed in depth on the Aquatic Plants Digest (see the archives for info). Other commercial solutions have also achieved good results.  The following are our procedures for dosing with Dupla products.

Duplaplant tablets should be added after a water change to replenish the trace elements removed with the old water. The tablets contain nutrients that are stable long-term and can last between water changes without oxidizing and are not toxic in a dose large enough to last between water changes. We follow Dupla's recommendation of a two week water change interval.

The tablets come in two sizes: 20 liter and 50 liter. You can tell which size you have from the container labeling – “100 tablets for 5000 liters” means 50 liter tablets. After the water change, add tablets corresponding to the amount of water you removed.  As a convenience, we change an amount of water that matches the tablets we use – 150 liters with 3 tablets. Note: when first setting up your tank, add enough tablets for the entire tank capacity.

Duplaplant-24 drops compliment the tablets and should be added daily. They contain nutrients that would oxidize quickly or would be toxic in a large dose (mostly iron).  A starting dosage would be one drop per 25 gallons of water but you should monitor iron levels to fine tune the dosage.  Try to maintain about 0.1 mg/l of iron (measured with a good test kit like LaMotte).  If iron levels are higher than this, you may find that thread algae will become abundant.

Since the tablets also contain iron, you may want to wait a day or two after a water change before you begin adding drops.  Again, monitoring the iron level will help you to determine this.

We also add Duplagan water conditioner after a water change.  This helps the fish keep their slime coat in good shape and also seems to contain things useful for fertilizing. I believe it helps chelate trace elements since it contain humic acids and it adds some magnesium.  It is an expensive product, so many consider its use optional.  We add the recommended amount – 25 ml per 50 liters changed.

Although the Dupla products seem expensive, they can be purchased in larger, more economical sizes.  We have found that they are actually cheaper per dose than many competing products that have a lower “container” price.  Daleco Master Breeder Products (800 987-1120) is a good source for Dupla products in larger sizes.


The job of aquarium filters is to keep the water "clean", both mechanically and biologically. For these functions to be done properly requires that the filters themselves be kept clean. If detritus is allowed to collect in the filter, two problems arise:

It would be best to clean filters every two weeks, but this is time consuming and will probably not get done. Canister filters seem to be especially prone to infrequent cleanings since they are usually "out of sight" and you generally can't see the dirt anyway. A simple prefilter before the canister would be a good idea if it was easily cleaned.

We feel that wet/dry or trickle filters are well suited to planted tanks because they are easier to clean and thus, will be kept cleaner.  We have arranged our trickle filters in such a way that we must clean the prefilter every three to four days.  The Amiracle filters we use have two mechanical sections: a sponge in the prefilter and a pad in the drip tray.  We have taken some extra drip tray pad material and wrapped it around the prefilter sponge.  This pad collects most of the detritus and dirt generated in the aquarium. As dirt builds up on the pad, it begins to clog and will start to restrict water flow through the prefilter. After three or four days, we will see that the skimmer is not skimming very well and will change the pad around the sponge.  This only takes five minutes, so we "cheerfully" do it.  The old pad is rinsed out and soaked in a bleach solution overnight and is ready to reuse.

The prefilter sponge stays clean enough that we only rinse it out when we change water.  Likewise, the drip tray pad stays clean enough that it is only changed one a month.  There is a final "polishing" sponge in the sump that needs to be rinsed out every month also. It tends to collect filter detritus; mulm and dead bacteria.

We don't use any chemical filtration (charcoal, resins, etc.), so obviously we don't need to replace those on a periodic basis.

Glass Cleaning

Even with a good group of algae eaters, the aquarium glass will still get some algae on it. At the very least, you will probably see hard green spots of algae that are obviously too much work for the algae eaters to remove. Typically, you will get a film over the glass and maybe even a green coating.  To maintain tank aesthetics, you need to remove this.

On glass tanks, a razor blade is a good way to clean the glass. A single-edged blade is recommended for your safety. A utility knife blade is even better since it is bigger and stronger. The ultimate is one of the "snap-off" utility knife blades -- they are typically 6" long before you start snapping pieces off. Do-it-yourself holders can be made from hobby shop basswood.

It is very important to make sure the blade you use is dried after each use. A little rust on the blade will scratch the aquarium glass and make an unsightly mess.  As far as I know, there is no practical way to remove scratches from a glass aquarium.

You can also use "pot scrubber" type pads to clean the glass, but be very careful that it has no abrasives in it. We tried some bought at a grocery store "for a good price" and found out too late that they were scratching the glass in our 120g tank. The green spot algae sticks very well to glass and I had to use lots of pressure. The light and angle was such that I didn't know I was creating scratches!

Acrylic aquariums are cleaned with special "buffing pad" that are specially designed to be compatible with the plastic. Luckily, the algae doesn't stick as well to acrylic as it does to glass. Even with the soft pad, some very fine scratches will develop on the inside.  You will note this when you change some water and the acrylic dries -- it will have a hazy look.  Luckily, acrylic has the same index of refraction as water and the haze disappears when wet. Likewise, any real scratches that happen are also invisible.

In both glass and acrylic tanks, brown or green algae will grow between the gravel and the front glass due to ambient light and light channeled from above. Algae eaters can't get to it, so the aquarist must deal with it.  We use a 6" square section of 0.080" styrene from a hobby shop as a scraper.  Simply push the styrene down between the glass and gravel and scrape the algae off.  This piece of styrene is also useful as a white background to use when you are wiping the glass -- it makes the spot algae easier to see.

The exterior of the tank also needs cleaning. Dust will collect on it and water will probably be splashed on it occasionally. Use a good quality glass cleaner on glass tanks but be very careful not to get it in the water. Squirting it on the cloth is safer than squirting it directly on the glass.  For acrylic tanks, use a special cleaner designed for acrylic and use a soft cloth, preferably 100% cotton.

Gravel Vacuuming

Many people wonder how you can keep the gravel clean in a fully planted tank. They also wonder if they need to.

We clean sections of the gravel when we pull plants up for trimming.  We usually pull up an entire section at a time and then lightly vacuum that area with the Python as we change water. We only vacuum the very top of the gravel to collect any mulm and detritus that collects at the base of the plants. We avoid cleaning too deeply as that might remove useful nutrients on their way down to the laterite (being pulled down by convection currents generated by the heating coils). 

Is gravel vacuuming necessary?  We think so.  We have seen tanks that use automatic water changers or no vacuuming and the bottom looks messy.  Almost all plants develop roots above the gravel and they tend to collect dirt that is floating around. The dirt in the roots almost looks like algae and we try very hard to keep algae invisible. So removing this dirt is just as important to us as fighting algae.

We like Python-brand gravel vacuums. The tube is big enough to sweep large areas easily and it is indispensable during water changes.  


Lighting is very important to the success of our planted tanks and light intensity is much more critical for success with plants than color tamperature. Lighting maintenance deals with maintaining the correct levels of intensity.

Fluorescent bulbs slowly lose intensity as they age.  To a lesser degree, they also change color temperature. This is not very obvious to us since it happens very gradually and there is no "reference" for comparison. Even though a fluorescent bulb will still light for 3 or more years, it is way beyond its useful life at that point. So the question is "When should you change bulbs?"

Well, of course, "it depends". A safe (but expensive) rule of thumb is after a year of use. This will keep your plants in a good, intense light field.  You should stagger bulbs changes so that all bulbs aren't new (or old) at once.  If you have a four bulb setup, change one every three months to avoid any massive changes in intensity.

If you have light loving plants and want to get the best out of them, change bulbs more often.  Brand new bulbs are about 20% brighter than their "design" lumens. They will loose this 20% fairly quickly over the first month and then continue losing intensity at a much slower rate.  If your light level is "on the edge" with brand new bulbs, you will have less intensity than you want over the long run.

Metal halide bulbs should be changed once per year (staggered if you have a multiple bulb setup). A metal halide bulb will lose about 50% of its initial intensity over a year.  Like fluorescent bulbs, metal halide bulbs are much brighter when new, but very rapidly loose this initial brightness.  Metal halide bulbs also show a more distinct color change over time. If you compare a new 5500K bulb against one a year old, you will notice the new bulb is very white and the old bulb is more yellow (the color temperature is decreasing). Check the lighting section for more details.

Besides changing the bulbs, is it a good idea to periodically clean the reflectors to make sure that as much light as possible is getting to the water.  If you have a cover between the water and lights, make sure it is kept clean.  If you don't have a cover, wipe any deposits from the water off the bulbs.

pH Electrodes

Unfortunately, the automation provided by CO2 controllers is not free. The pH electrodes or probes are sensitive things and must be kept clean and calibrated. We like to check pH with a manual test kit monthly to determine if the probes are still working properly.  If we notice a slight drift in pH, we will "tweak" the controller setting to read correctly. If it starts to drift too much, we will clean the probe and recalibrate it.  When we notice that the probe is very slow to respond to the water pH versus the calibration solution pH, we will replace the probe.  They have about an 18 month life, including the time it spent at the retailer.

Cleaning is done with a soft cloth and a mild soap solution like Ivory dishwashing liquid . The probe tip is very fragile, so be gentle. After cleaning the probe, it must be recalibrated.  Calibration solutions are available from where ever you bought the probe or controller. We use two solutions, pH 7 and pH 4. To calibrate the probe you need a small container of each solution (don't dip the probe into the stock container!) and two rinse containers with distilled or tap water.

  1. Make sure the solutions are at aquarium temperature
  2. Dip the clean probe in pH 7 solution, wait for readings to stabilize then adjust the "standard" or "calibrate" setting
  3. Rinse the probe in pH 7 rinse water
  4. Dip the clean probe in pH 4 solution, wait for readings to stabilize then adjust the "slope" setting
  5. Rinse the probe in pH 4 rinse water
  6. Repeat steps 2 through 5 until no adjustment is needed at either pH point.
  7. Rinse the probe and put it in the aquarium.  If it responds to the aquarium pH very slowly, it is time to replace it.

Plant Pruning

The major maintenance activity in a planted aquarium is pruning the plants. This can range from daily "sculpting" to biweekly or monthly thinning, depending on your style. Rumor has it that Takashi Amano has a crew of garderners that spend hours each day manicuring the tanks at the ADA facility so that each tank is perfect all the time. Most folks let the plants do their own thing and only do trimming to keep them under control. We fall into the second group.

Detailed pruning can be found in the plants section but this section has some general guidelines.

Different techniques are needed for different plant types. We prune stem plants at each water change (bi-weekly) and perhaps remove old leaves of large rosette plants at the same time. Plants that spread with runners are allowed to run amock for months then are completely pulled up, trimmed ruthlessly and the best speciments are replanted.

Crypts are usually left to their own devices and tend to form large groves with densely packed plants. We will sometimes pull up plants on the outskirts of the grove, containing it to a reasonable area. Other times we will uproot the entire mass, select the best plants and replant those.

Anubias grow very large in our tanks. They are usually background plants so we let them go for maybe a year or so. When they get too large and start to affect other plants by shading them, we will pull them up, do some brutal trimming and put a few back in.

Really big sword plants again are left alone for long periods. When they have gotten too big, they are removed (quite a job!) and either have the rhizome trimmed back or are replaced with a new one. We have been propagating Echinodorus horemanii (red variety) for quite a few years. We will trim the rhizome, put a few peices of the rhizome back in the tank and find a home for the Mother Plant. We have done this cyle four times already.

The bottom line is plants do not suffer from brutal trimming. Don't be afraid to pull them up and rarrange things!

Water Changes

Changing water is an important part of good aquarium husbandry. Many people think that you change water only to reduce nitrates that build up from biological filtration. Nitrates higher than 10-15 mg/l is a good indicator that water needs changing but there are other factors involved also.

Nitrates aren't the only toxins from waste products. I don't have a list, but one example is alleochemicals from plants. Plants "protect their turf" by creating chemicals that help keep other plants away from them. Some terrestrial weeds have honed this to a fine art. Water changing is the only way to get rid of toxins like these.

Changing water is also a good way to keep buffering and trace element levels up (if you have good tap water). Water changing also removes excess salts from building up if you add harder tap water to make up for evaporation.

We change about 50% of our water every two weeks. Becuase we keep larger fish in planted tanks, we need to change this much to keep nitrates down. People with lower fish loads can change less water if they desire.

Python water changers are very handy for this purpose. Because we have three large tanks, we have two Pythons, one to drain one tank while the second fills the previously drained tank.

Some people are concerned about wasting water when using the "pump" part of the Python to suck the water out of the tank. To avoid this, we use the Pyhton as a siphon for draining and direct the waste water to the garden and trees around the house. We bought an extension for the draining Python so we can route the water to all areas of the garden.

For filling the tank, we run the Python right from the faucet into the tank. We have only low amounts of chlorine in our tapwater, so we don't do anything to condition it except to squirt some Duplagan into the water as we fill the tank. Our water is also very soft, so we can simply add some hardeners as we add water to make it right for the fish.

We used to have a hard time getting the temperature right. One of us would stand at the sink and adjust the water as the other stood at the tank and said "warmer, warmer, cooler, warmer ...". Now we have a Second Nature liquid crystal thermometer stuck on the kitchen faucet. We have the kind with the moving line instead of the dots. Works great and they are accurate! When you buy one, look through all of them on the rack and pick one that shows the same temperature as most of the others. There are always some odd ones!

Water Testing

Water testing is am important part of plant husbandry. As Dupla says, "The control of all variables" is one of the 10 Golden Rules and you can't control them if you don't know what they are.

Many people claim that testing is a waste of time and money because they can tell what's going on just by looking at the tank. This may be true in some cases and or for experienced people. But how do you get that experience? By testing and observing and correlating observations to measured parameters. We can now easily tell if we have too much iron; long string thread algae begins to grow. Too little iron and the plants look a little yellow. We can adjust doing of daily drops accordingly. But if measurements aren't made once in a while, we can be fooled. Likewise, if nitrates are too high in the discus tank, they begin to look a little dark and we know it's time for a water change.

But when you are just setting up a tank, you have don't have a baseline for what the tank should look like with proper conditions. For this reason, you need a range of test kits to help you get the experience. If you're like us, you'll test like crazy for quite a while then begin to find out that just doing it every so often makes more sense.

For some measurements like pH, it will take a large deviation from normal before things look funny. And by that tine, the change in pH may have produced some serious stress in your lifestock. In this case, an ounce of prevention is well worth a pound of cure.

And as far as experience goes, I often hear interesting stories. One gentleman was asking me about his fish fry were acting funny. It sounded a lot like high nitrates to me, but he assured me that was not the case "based on his experience". After more discussion, he mentioned that the smallish tank had a large brood of convict cichlids that were feed heavily and he was only doing his normal 10% water changes. I strongly suggested testing for nitrates and he grudgingly did the test. He reported back, "in the midst of massive water changes" that the nitrates were 160 ppm!  (I consider 25 ppm pretty high).

Many people are surprised at the cost of high quality test kits and will opt for cheaper "hobbyist" grade kits. Many people report poor results with these for two reasons: generally poor design or quality control and they've been on the shelf too long and the reagents are old. I heard many cases of people trying two ot three different brands of hobbyists kits, paying a total amount greater than a good test kit, and then buying the decent kit they should have bought in the first place. It's your money. Even worse is using a bad or out of date test kit and thinking there is no problem when there are actually very high levels the thing you're measuring. Cheap nitrate and iron test kits seem especially prone to this.

We prefer LaMotte test kits for almost all of the tests we do. Other aquarists have also reported on the high quality of Hach test kits. You can't go wrong with either brand. Both take credit card orders and I know for sure that LaMotte does international sales.

Which test kits should you buy?  Here is a prioritized list of the tests in the order we think you should buy them. We consider the tests marked "required" as indespensible for planted aquaria. "Optional" test kits are nice to have. The other tests are mostly useful for people who are intensely analytical (like us!). We recommend buying individual kits - the "collections" offered by different companies often include kits that are of little value to planted aquaria.

One thing to note: people are often confused over the terms "parts per million" (ppm) and "milligrams per liter" (mg/l). Various test kits will usually report in one or the other. For our purposes, they are the same. A milligram is one 1/1000 of a gram and a liter has 1000 grams, so a milligram per liter is one part per million!.

pH Test Kit (required)

LaMotte model AG-21 code 7462: 6.0 to 7.4, Octet comparator

This is the only pH test kit you'll ever need! The octet comparator is a test tube holder with solution samples for the different values the kit measures. This is much more accurate than the paper cards cheaper kits use. It is improtant ot note that most of the cost of the kit is for the comparator. Refills for the reagents are very cheap! The kit, like most of the LaMotte kits, is good for 50 tests. it's very fast and easy to use: filla sample tube with water, add 7 drops of reagent, shake to mix and use the comparator to read the value. With practice, you can deduce pH to 0.1 or even 0.05 units resolution!

Even if you have a pH controller, it is wise to have an accurate manual test to make sure the probe is still calibrated. It is also good for checking the pH of water your new fish from the fish store came home in -- it may take longer to equilibrate the pH than you think!

Alkalinity Test Kit (required)

Tetra "KH" Test: 0-10 dKH and higher, 1.0 or 0.5 dKH titration
LaMotte model WAT-DR code 4491-DR: 0 to 150 ppm (and higher), 4 ppm titrator

When using CO2 injection, you must know what your carbonate hardness is and adjust it accordingly. Note that the Tetra "KH" test kit is simply an alkalinity test. If there is are other chemicals in your water that affect alkalinity, the test kit will not read true values of carbonate hardness. If bicarbonates are the only buffering compounds in your water (which is ideal in a planted tank), then alkalinity is the same as carbonate hardness. Unfortunately, this is difficult to determine unless you know that exact make-up of your water. If your tap water is very soft or you use RO water, you will increase the KH by adding sodium bicarbonate. In this scenario, you can feel assured that alkalinity and carbonate hardness are equal.

Of the two test kits, I feel the Tetra is just as good for our purposes and is easier to use and cheaper than the LaMotte.

Hardess Test Kit (required)

Tetra "GH" Test: 0-10 dGH and higher, 1.0 or 0.5 dKH titration
LaMotte model PHT-CM-DR code 4824-DR-LT: 0 to 150 ppm (and higher), 4 ppm titrator

These kits measure calcium (Ca++) and magnesium (Mg++) ions in the water. It is important to have proper general hardness for the health of both fish and plants. You can adjust GH to suit particular species that perfer soft or hard water or you can set a compromise level that is OK for all the species you keep. One of the consequences of improper general hardness is poor structural formation in plants (twisted leaves, for example) and fertility and internal organ problems in fish.

The Tetra kit is cheap and easy to use and is sutiable for our purposes. The LaMotte kit measures both Ca and Mg harndess, so you can fine tune your additives to achieve specific proportions of each.

Nitrate Test Kit (required)

LaMotte model NCR code 3110: 0.25 to 10.0 ppm Nitrogen (1.1 to 44.0 ppm Nitrate), Octet comparator

Nitrate is a very important measure of the health of your tank. If it is too high, plants and fish will suffer from its toxicity. We think levels greater than 25 ppm are a problem, especially with sensitive fish like discus or rams and plants like Ammania and Rotala. Likewise, nitrate levels that are too low (below 5 ppm) will cause the plant growth to be nitrate limited and all the nutrients in the water will be used by algae. Many people assume wrongly that zero nitrates are a good goal. This is great for reef tanks but disastorous in a planted tank. If you have a light fish load, this is a very important thing to check.

Iron Test Kit (required)

LaMotte model P-62 code 7787: 0.05 to 1.0 ppm, Octet comparator

Iron is very important for plant growth and also as an indicator of proper trace element levels. Most trace element solutions are mostly iron with trace of other elements. If the iron levels are correct (about 0.1 ppm) and the manufacturer created a balanced mixture, you can feel assured that all other trace elements are correct. If iron is too high, algae will grow too fast and if iron is too low, plants will be chlorotic (yellow).

Phosphate Test Kit (optional)

LaMotte model PAL code 3121: 0.0 to 2.0 ppm, Octet comparator

Generally, if nitrates are at a proper level, phosphates will be OK also since they are generated from fish waste in certain proportions. A phosphate test kit is good if you suspect an outside source of phosphates like tap water or commercial buffers.

Dissolved Carbon Dioxide Test Kit (optional)

LaMotte model PCO-DR/AG-38 code 7297-DR: 0 to 150 ppm, 1 ppm titrator

CO2 can be measured by a test kit directly or can be inferred from accurate pH and KH measurements and a pH/KH/CO2 table. If you suspect that your KH (alkalinity) test kit is being affected by things other than carbonate hardness, a CO2 test kit is a good cross check. If the results don't match, suspect the alkalinity test since alkalinity is usually affected more by other buffers than the CO2 test (although it can be fooled by strong mineral acids).

Dissolved Oxygen Test Kit

LaMotte model EDO/AG-30 code 7444: 0 to 10 ppm, 1 ppm titrator

When plants strongly photosynthesize, they generate oxygen. When the water reaches saturation, bubbles can be seen forming on the plant leaves or bubbling from cuts and scrapes on the plants. The bubbles are usually enough of an indication that you have lots of oxygen, but maybe you and your friends can have Oxygen Saturation competitions. "Mine was 112%!" "Oh, yeah, mine was 119%!"

Ammonia Test Kit

LaMotte model NANR code 7418-01: 0.02 to 1.0 ppm, Octet comparator

Ammonia testing is only useful for tracking the start of the nitrification cycle in a new tank or troubleshooting problems with the biofilter in an established tank. The amonia peaks in a planted tank will be very low and aren't worth worrying about. But, if you're anal retentive, it's a fun test to do and makes a neat chart! If you're going to to it, better have a good test kit...

Nitrite Test Kit

LaMotte model LNI code 7674: 0.02 to 0.30 ppm, Octet comparator

Ditto the ammonia test. More points for that chart!

Total Dissolved Solids Test Meter

LaMotte model TDS-1: 0-1990 ppm, digital display

Many fish-only aquarists used a TDS meter in lieu of hardness measurements. TDS are defined as all the solids left when water is evaporated. We think of hardness as only Ca and Mg while TDS is that plus other solid material (sulphates, phosphates, etc). I've not found a TDS meter very useful for a planted tank. I thought at first I could infer other trace elements like potassium and manganese by subtracting all the the other test kit values from a TDS reading but it didn't work out very well.