fishtk75

This is the first time I used it.
I did as you have on the bottle directions one capful for 50 gallons.
for my 58 gallon tank.
Two days four rainbow died.
Is there some fish that this is bad for?
Is there other direction for dosing?

IceH2O

Never had it kill any fish and I have 6 Rainbows in my planted tank.

I did have it damage my biofilter but that was because the wrong directions were on the bottle and I was to dense to realize cap size. So I added 3-4 times the normal dose for a week. Seen the tank get cloudy and tested for ammonia and nitrites both which were at .25 -.5, took about a week of daily pwcs to get around the minicycle.

Your dose was correct and shouldn't have affected the fish so you need to look at other options.

fishtk75

thanks I will put half the dose to see what happens.
I know before I had added any the water changes I made the plant would bubble alot after.

Seachem

In regular dosing, Excel is harmless to the fish. If overdosed, it can bind up dissolved oxygen in the tank, causing stress to both the fish and the bacteria, which will cause your "minicycle." It is very obvious when this happens, though, because the tank goes cloudy and the fish start gasping at the top. This effect is usually not seen until you reach roughly 5 times the recommended dose. I would expect that it is more likely a pathogen that affected the rainbows. Rainbowfish are notorious for harboring a bacteria that only appears about two weeks after shipping. It can be cured easily with kanamycin, but if you're not looking out for it, it can hit hard and fast, and will generally only strike rainbows.

fishtk75

Seachem
Is there things not to put in with Excel that will make the water toxic?

Seachem

The only thing that jumps to mind is Cupramine, which is not something you would want to use in a planted tank anyway. Other than that, I know of no harmful interactions.

fishtk75

Seachem thank you for your help.

Seachem

You're welcome.