by Bill Pabst
Author’s note: This "article" evolved from an email I wrote to a fellow hobbyist about her new planted tank. I don’t pretend to make any claims about the correctness of my recommendations, or about the quality of brand-name products mentioned. This is just what works for me. I am sure there are experienced plant growers who will read this article and be appalled at my lack of precision. I welcome your responses, and perhaps this article can serve as a beginning for a dialogue about keeping planted tanks.
For your new plant tank - definitely throw a school of Danios or other cyclers in there. I have been through a couple of roller coaster rides of cycling, different types of algae, lack of growth, and non-lush overgrowth problems with my planted tanks. They are finally settling down (for now), and the well-cycled water definitely helps, as well as algae eating residents. A combination of Siamese algae eaters and Otocinclus catfish do a good job, but keep in mind that they only act as a sort of preventative medicine for beard algae, by eating it before we can actually see it. They can be part of a solution to an already established algae problem. Corydoras catfish seem to help my planted tanks too, perhaps because they clean up uneaten food before it rots, or they help stir the gravel a bit with their rooting.
As for the 8.5 pH, try to bring it down to neutral 7 or a little under. I can’t recall the exact reason, but almost all aquarium plants tend to stop growing, or wither and die, at alkaline pH. I am currently trying out Seachem’s "Acid Buffer" and "Alkaline Buffer," but I don’t think the directions on the bottle apply equally to everybody’s water, everywhere.
Adding C02 will lower pH as well, but maybe not enough. There are varying levels of how accurately one can measure the CO2 level in the water, ranging from pricey electronic monitoring equipment, to water test kits, to nothing. I lean towards the latter, because I know the "D.I.Y." (do-it-yourself) CO2 system that I use probably doesn’t put enough in to cause a problem, and I have never found a fish gasping at the surface. CO2 also acts as a wonderful deterrent to beard algae. It makes the algae growths melt away. To test the pH I use Mardel’s "Aqualab" test strips, which are imprecise but very quick and accurate enough to tell you if there is an unexpected spike or drop.
One lesson I learned - if you get an algae explosion, don’t do a big water change, that just encourages it. Rather, add de-ionized or reverse osmosis water, which can lower the pH and discourage algae by starving it of phosphates and other nutrients. Prune back the worst affected plants, severely if necessary, and they will eventually grow and out-compete the algae for nutrients and light. The more light the better; I have good luck with Hagen "Life-Glo" aperture fluorescent bulbs, but they are more expensive than other brands. I have also had success with Aquamarine’s "Phosphate Eliminator," which is actually a biological agent that eats phosphates but doesn’t disrupt the biological filter.
Another factoid that, when I read it, made me slap my forehead, is this: aquarium water can be, if done right, simultaneously high in dissolved carbon dioxide AND oxygen. It’s not like our lungs where one gets exchanged for the other. So keep in mind that surface movement increases the liquid/gas interchange, which is good for fish that need the oxygen, but mostly wastes the CO2. "Real" plant growers usually have some kind of diffusing device that increases the amount of time the CO2 bubbles spend in contact with the water. I have Aquaclear filters and I set them on the low setting to decrease surface movement, until they get a little clogged, and then the high setting becomes low. A side note - if you are running Aquaclear or other filters that have the replaceable carbon bag inserts, take them out. They can suck up the iron and trace minerals that plants need, and can leach phosphates, which leads to nasty hair algae. In my Aquaclears I use two sponges instead, and once in a while take one out and rinse it, so that the biological filtration isn’t totally lost, but the mechanical is replenished. In fact I have used this system elsewhere, including plant-less fry grow-out tanks, and they don’t seem to miss the carbon one bit.
Another idea is to turn the filters to the high setting at night, when both the fish and plants are consuming oxygen, then turn them to low during the day, so that the CO2 builds up for photosynthesizing. This is easy enough to do at feeding time, but somehow hard to remember.
I fertilize once a week with Aquarium Pharmaceutical’s "Leaf Zone," which has chelated iron, which is supposed to remain in liquid suspension until used by the plants, instead of oxidizing. I also add the directed dose, or less, of "Black Water Extract," "Plant Gro," or "Freshwater Total" for trace elements and nutrients.
This is how I do the CO2: I use the half-gallon plastic jugs that cranberry juice comes in. I tried at first with 2 liter soda bottles, but the plastic that the caps are made of seems less cooperative for sealing shut with glue. The jugs also have a wider mouth, which is makes for less mess when pouring out the smelly used mixture. I put a hole in the cap with a nail heated up on the stove. Then I put the airline tubing through and glue on both sides with "Goop" brand glue. I bought the plumber’s variety at Home Depot and it seems to live up to its reputation. I guess it would be better to use a piece of rigid tubing and a rubber stopper for that part, but I don’t have any. The longer the tube-line into the tank, the more pressure is needed to get the bubbles going. I always put a check valve just above the bottle. This requires even more pressure, but it reassures me that my tank won’t siphon out in the event of who-knows-what.
The recipe recommendations I have seen on the web vary. I am using about 1 1/2 to 2 cups of sugar and 1 generous teaspoon of yeast, poured through a funnel and then shaken. I definitely recommend buying a jar of active yeast instead of the expensive little packets. I leave the bottle about a third empty, in case the mixture foams up into the line, but this has never happened so far. I think starting it with warm water helps the yeast activate, but definitely stir the mixture to get the sugar dissolving. It seems to take a day to get started, and lasts varying amounts of time depending on temperature. I have been restarting the mixture about once a week by pouring out most, but not all, of the crud and putting fresh ingredients in. I think it also helps to use water that has dechlorinated by aging rather than chemicals. If it can’t seem to get going, try a little more yeast. If it runs out quickly, try a little less yeast, or more sugar. If the mix smells like beer, it’s cooking away. If it smells like wine, it’s probably starting to run out, but can be encouraged to work for another day by shaking the jug.
This article first appeared in PVAS’s Delta Tale, Vol 32, # 1