A List of Recommended Levels and Parameters
By Tom Barr

A careful eye on the plants is one of the best things you can do. What to do if there's a problem is why I wrote this up in the first place.

Lights are not really an issue unless you just don't have enough but the color temps don't mean hay. I've gone through from 3050K with the QTL's to 6700K to 8000K MV bulbs. They all work well but the 6700 to 5000k seem about the best but many plants grow great at redder color. Some blue does help but to a lesser degree than red. Good lighting types are Metal halide, T-12 or T-8 standard Fluorescent, Power Compact Fluorescent and VHO lighting systems.

Sooooooo, all that's left is ? CO2 and Trace/Macro elements right? If you have good lighting then the next item to master is CO2 which involves KH and pH. At a KH of 4 which is about the best range (mine's 5-5.5) all you need to do is dial the pH in with CO2 gas additions to about 6.6-6.8 and try to keep it in this "range" throughout the day. If it goes over or under somewhat it's OK. Add Baking soda to get it (the KH) up (for your tap water in SF anyway). My water has it pre-added in Marin <g>. If it starts at 6.4 or 6.5 in the morning and hits 7.0 later right before the light go off, that's all fine and dandy too. This might be a typical rise during a day depending on your tank's lighting and other factors. A rise of .2 to .4 is what you would like to hit on a daily basis. Of course if the plants are growing and looking fine don't mess with it.

There is a nice table and a more in depth discussion on the web on The Krib. By testing your KH and pH and adjusting each or both of them you adjust your CO2 levels in your tank. So a KH of 4 will give you a CO2 reading of 30 mg/l if you have a pH of 6.6. And if you raise the pH up to 6.8 you'll now have 19mg/l and if you take it up to 6.9 you'll have a CO2 content of 15mg/l all of which would do nicely for your tank. So just add something for KH and get it to 4dKH and dial the pH in with CO2 till you have between 6.6 and 6.9 pH. This is all you need to do for CO2. Got harder water? Adjust based on the KH/pH table. It's cheaper/easier to add more CO2 than to soften your water /add RO water etc. but you will need more CO2 in solution to drive things down. Some folks use H2SO4 to lower KH. Check APD archives for more info.

I would move on to NO3 from here although Ca and Mg are very important components of GH. Many fertilizers add this or at least Mg. You can add SeaChem's Equilibrium for this to get it up to about 4-5GH. It adds both Ca and Mg and K and Fe too. You can also add Calcium carbonate to get equal amounts of GH and KH but this lacks Mg.

NO3 seems best at 5-10ppm but this is a bit more flexible "range". You may only want to add weekly or perhaps everyday a little bit each time. Some may have 20ppm at the beginning of the week after adding some to come to about 2 PPM at the end of the week. Some may want to keep a narrow day to day level of 10ppm(+ or - 2ppm) by adding and testing. I've had higher levels than this but the plants I doubt need the higher levels unless you are using 5watts+ per gallon or more etc. I've had some tanks in the 50-75ppm range before with little to any algae but also had lots of light and CO2 etc. I also did 50% water changes so things didn't keep building up but were removed after a week or so with no harm done. How much each tank "eats" should be tested first then a program can be implemented with less testing and a good idea of the tank's needs.

Fe (iron) can be used from a few different sources. Iron filings in the substrate, flourite, laterite, etc can be added in. The water column should have about .2-.5ppm although myself, Karen's, and a few other's water have been higher than this without issues. Mine was 2ppm at the Nov open house for instance. I keep some tanks lower on purpose (.2ppm or less) but these have substrate based iron sources also. These tend to be lower lighting tanks also that get less attention. Plants can do fine for up to three weeks without iron in the column so it can be used as an algae control/limiting nutrient/agent.

The general trace element fertilizers that are sold have the other elements in there also but iron is the big one to measure. Basing the others off of this reading of iron seems to work fine for the other elements in the mixture for most all tanks. If your having algae problems back off the fertilizers like TMG or Kent etc. and do a water change and add the GH and KH and the KNO3. I add Tropica Master Grow(TMG), and had good luck with Sera and SeaChem's flourish and Flourish iron. Mr. Dixon seems to say that adding a small extra "spike" of iron from SeaChem's flourish iron adds to the sparkle in his tanks and his plant's health in addition to his using TMG. I think adding more TMG if you have a handle on your algae problem is a wise move, even doubling to tripling the recommended amounts in a well running tank.

I have a tank that gets no iron to some every two months or so. It has Flourite gravel and no algae at all. I haven't cleaned the glass for 4 or five months now. There are some nice crypts and A. reineckii that are nice and red. The hairgrass is very short, about 1 -1 1/2" tall. Some plants are held back/limited by not adding anything to the water column. But this also stops the algae very well and also keeps the pruning down somewhat. This tank has a simple filter and only a few fish that get fed heavily once a day with flake food. Just adding iron to the substrate is a method of limiting algae and you can try this or add a small amount after a water change if most of your iron is in the substrate. Algae doesn't have roots after all.

In Marin there's a high level of PO4 in our tap water. 1.12ppm or so and I do large water changes typically. Around 25-50 or 70% weekly. I really don't need to add it in my water. My PO4 levels fall quite fast later in the week. We tested about .5-.6ppm after 3 days afterwards a 50% water change with good feedings and OK growth rates. Some folks add it by feeding with fish food which contains some. Steve Dixon adds it by using K2PO4 at the rate of .2ppm or so or about an 1/8 of a gram (about one spoon full of those NO3 power reagent spoons in test kits) for each 1/4 teaspoon of KNO3. K2PO4 is available from Hach testing along with some good test kits.

Recommended Doses:

DoseTarget Note
pH 6.5 to 7.0 Lower with CO2 gas only.
KH 3-6 degrees Add Baking soda or SeaChem's Alkaline buffer to raise.
Nitrate (NO3) 5ppm-10ppm Add KNO3 (Potassium nitrate) a.k.a. stump remover. Fish load and feedings.
GH 2-8 degrees Add Sea Chem's Equilibrium to raise. Or CaCO3 for both KH and GH.
Iron (Fe) 0.2ppm to 0.7ppm+ Add fertilizer such as TMG or Sera or Kent etc.* Note: If you have a well fertilized substrate with lots of iron in it, this level can be lower.
Phosphate (PO4) 0.2ppm to 0.5ppm Add K2PO4 or fish food or sometimes in the tap water already.
Potassium(K+) 20-30ppm Add K2SO4 and/or KNO3 to boost if you also need NO3. Also in Equilibrium/TMG/Kent etc.

If any thing is over these recommend levels do a water change to lower it.

Recommended Levels:

Temperature: 68 to 84 F and a target of 76 to 78 degrees F or 25 C
Water flow: 3 to 5 times tank volume per hour (little to no surface movement) or less
Fish load: Light to moderate/algae eaters should be added. Snails are good for this(pond, MTS, Ramshorn)
Lighting: 2 to 4 watts per gallon of FL,MH or PC's

If something is causing you problems in your tank and you test -or not- you can always do a water change then build up these levels to the proper ranges and you should not have problems as long as you keep up on things. Testing helps you from shooting in the dark. It's worth the money and time to test. You'll pay for it if you don't, lord knows I have. So have many others. It's good to learn from experience as long as it's not your own!

Suggested test kits:


Pinpoint pH monitor(much better)
Red Sea low range(cheaper)


Most all test kits are decent such as Tetra/Sera etc.


LaMott(much better)


Same as KH


Hach(much better)
Sera or SeaChem(cheaper)


Hach(much better)


Aquarium Landscapes

If these parameters are in a good range you should have only minor issues, if that. You only need light, CO2 nutrients and a balance of these factors and of course a little patience and an eye/desire for the planted tank!

My tanks have the following ranges:

  • PH: 6.5-7.0 KH: 4.5-5.5 GH: 8-9 PO4: 1.12ppm average Temp: 82-75F Fe: .1ppm to 2ppm depending on the tank NO3: 4ppm to 30ppm but try to keep it in a range of 5-10ppm

  • K+: 20-30ppm

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