For how long did this battle go on? It often takes about 3 months until a new tank achieves a "balance". During that period, there can be massive overgrowth of certain things, especially brown algae. During this time, it's ugly, but if you can "ride it out", the tank will eventually not have brown algae at all. I have seen this happen many times. It's very frustrating, but things do get better.
Fish products are not normally tested on amphibians, and they never list the actual ingredients. Thus, I don't think anyone can give an accurate answer to your question. The other problem is that products that kill algae may not have any effect on brown algae. As Kaysie mentions, brown algae are diatoms, which are very different from green algae. So my advice is that it isn't worth the risk, but of course you have to make your own judgement.