Killed another fish...

[FishyJoe]

Well, I did it again. I killed another fish. My son's 5g tank, with the guppy and the cory, was getting extremely full of algae. So, I decided to scrape the algae off the walls, like I've done before. I have done this a number of times, but I've never been able to get the brown algae that sits right above the sand on the glass, because it seems to be too tough. So I used a plastic scraper. I also took out the small barrel that we purchased for the tank (it's a fish store "toy"), and cleaned that off with a nylon scrub brush. Both of these things I've done before. But due to the excessive (in my opinion), algae being scrapped from the walls, it was all floating in the tank water. So I did a water change. I also added a bit more black sand because the plants we had needed a little extra sand to keep them from floating up. So now I introduced two changes. There was also tons of algae on the biomax mesh. I did NOT rinse the biomax, but lightly with my finger took the algae off the mesh, without touching the pellets.

So now three changes. Why do I do that? Well, one of those things seemed to cause the guppy to swim stationary at the top in one spot for about 12 hours, then died. I would not have done the water change or scrapped the algae off the biomax if the algae wasn't getting to be overwhelming and too fast. I've read through the boards, and I cannot find a suitable answer to controlling algae without getting snails.

I did a water test and got the following results:
Nitrate and Nitrite = 0
pH = 7.5 (it should be 7.0 but have no idea how to correct)
kH and gH were in range (don't recall the number).

 

[foxgirl158]

Ammonia?

 

[Alice B]

after scraping algae, just for future reference, may i suggest a fine fish net waved thru the water to grab the particulate, avoiding fish.

Too large a water change, In MY Honest Opinion, can contribute to trouble. There is some beneficial bacteria in the water. I don't like deep sand beds, they get pockets of anaerobic bacteria that convert waste to hydrogen sulfide, black stuff, which is toxic when released.
Some people recommend 100% water changes and deep sand beds, and I just do things my way, based on my experience. As far as algae growth, without waste (maybe inadequate filtration) and light, there should not be excessive algae. Brown algae is often a diatom bloom associated with cycling, and that occurs when too large a water change on too young a tank, imho.