regarding Ted's question on the use of carbon I am afraid that there are some understanding problems.
Why should pheromones occur in a rainbowfish tank and who said that they would reduce growth rate?
According to my knowledge pheromones are special sex hormones which occur chiefly in livebearers and
not in egglaying fishes. Please let me know if you have any other source.
Carbon use in the filter will reduce any suitable water ingredients in a way of a physical half-life time.
Thus it is not possible to remove ingredients totally, only partially. However, if you have any problems
with the tap water carbon may help you. What are suitable ingredients which may be removed? All large
molecules, like hormones, most medication ingredients, but also pesticides and other unnecessary tap
water ingredients. In Germany, however, many tap water provider already use carbon filters to remove the
dangerous ingredients before they reach the households. Carbon does not remove surplus ingredients like
nitrate, nitritre and ammonia iones. So I eould use it just if I had tap water problems or if I wanted to
reduce any medications to protect the plants.
Carbon has a great surface (if you use the right one, which may be called activated). However, if this
surface is filled, the carbon has no typical reaction. It then is nearly useless. You have to change it rather
often.
I think the best way to reduce water ingredients you don't want to have is to change the water as often as
you can and additionally take some filters - that may at minimum be a bubble foam filter already in a fry
tank.
Harro