Algae vs. Hydrogen peroxide

I'm afraid I can't say. I treated a tank full of malawi cichlids with it. The water was very hard, but I didn't see any deleterious effects to the fish. I haven't used it to get rid of algae, though.

I used it to stop fish from scratching, which it did very well.

For those of you who don't know how to measure out 1 ounce of h2o2 (like me): 1 fluid ounce is equal to six teaspoons. So add six teaspoons per every ten gallons of water.

Update: Looks like the snails will make it. Much of the fuzz that had attached itself to the "Red Rubin" sword and Anubias plants is now easy to dislodge and is coming out. The Gambusia are just fine...Seems to have been effective, the plants don't seem to have been stressed. I will do a little pruning and planting tonight.

Now...that was with a low pH high, CO₂, soft water tank with what could be considered the "cockroach" of the Piscine World.

What happens when the chemistry is different. Like WAY different(Super hard, pH of 9.0+, high O₂ ), and the fish are extremely sensitive to changes? I'm speaking specifically of Lake Tanganyika Cichlids... Does Hydrogen Peroxide behave differently at higher pH and when there is a lot of carbonate hardness? My chemistry is really rusty...so please be gentle....

I tried this method in my South American planted tank, tds = 200 ppm, 6.8 pH, at 1 ounce/10 gallons and killed about a half dozen cardinal tetras and three Otocinclus. I think it was due to the toxins released by the dying/dead bga, I had a quite an infestation of the stuff, would it have been better to start off with a lighter dose and kill off the bga a little at a time? I typically don't use carbon on my planted tanks, but with a heavy infestation and subsequent die off of bga I think I would recommend a bag of carbon for a day or two. A question for those of you who use H2O2 as part of your regular maintenance, do you continue to use a full strength dose or a lower, prophylactic dose?

at 1 ounce/10 gallons

I seldom find a need to dose more than 1Tbsp/10 gallons.

I tried dosing an experimental batch of infested rosy reds last week at the higher rate and had a 50% mortality within 36 hours. One other died a few days later. I can't tell whether the fault lies with the H2O2 or the various critters that were already infesting them. The two remaining fish look fantastic and healthy.

I did pull one of the fish out and examined with a 30x jewelers loupe and gave it a 20 second bath in a stronger H2O2/H2O dilution and could see that the parasites were very much agitated by this and went into violent throes (the worms, anyway). The two fish that are still alive had the same sort of worms, hanging off of them in cysts either on the surface of the skin or just under it. But there is no sign of infection in them now.

I seldom find a need to dose more than 1Tbsp/10 gallons.

Thanks, I'll try that dosage next time.

I recently treated an unplanted tank that holds longear sunfish, shortnose gar and stonecat. I had a filamentous algae problem since I never cleaned the wood I placed in the tank. One piece really went nuts with the stuff and the algae spread throughout the tank. The algae removal was a side issue since my sunfish group have been scratching despite the incredibly high salt concentration. I treated with 1 fl. oz. per 10 gallons and knocked much of the algae down and have noticed a sharp decrease in scratching. I'm pretty happy with the results.

I treated a tank with H2O2 that has high PH containing 2 adult Jewel Cichlids and about 100 fry. It was completely swamped under with algae. It took a few tries, but it killed most of it, the rest, I easily pulled out in one big clump. Virtually all algae is gone now, with no adverse effects to the fish. (There was some hornwort in the tank that suffered, but who cares?) This method seems to work pretty well. Thanks for the advice.
-Thom

Yep, you'll burn the tips of the less developed plants like hornwort and elodea, but it bounces right back.

Another way to look at it is to ask "where those plants would be covered in alleopathic periphyton?"

Todd

There are no long term effects because the H2O2 very quickly breaks down into water and oxygen.

I've been experimenting more aggressively with it on external parasites with great effect. I don't really have an algae plagued tank to try it on, though.

I have a question concerning brackish water (1.010) and H2O2...is it still safe at this level? I have a few Gambusia, Sheepshead Minnows, Mummichog, and mollies. I've not really encountered a problem so far, but was wondering if this would be useful for the arsenal.

I have a question concerning brackish water (1.010) and H2O2...is it still safe at this level? I have a few Gambusia, Sheepshead Minnows, Mummichog, and mollies. I've not really encountered a problem so far, but was wondering if this would be useful for the arsenal.

Now, that's an interesting question. I've never tried it on the mummichog tank. Do you have brackish plants in there?

Nope, you have not crashed your good bacteria. Many of us have used this technique.
Problems I have seen.
Inverts freak out! Crayfish in particular.
I have also seen it affect Pternotropis negatively.

Can anyone explain why it doesn't seem to kill the bio filter bacteria?

When you say inverts "freak out", does that mean "freak out and die", or "freak out but get over it"? Sounds like pulling crayfish out of the tank (if possible) would be a good idea, eh?

-Jase

When you say inverts "freak out", does that mean "freak out and die", or "freak out but get over it"? Sounds like pulling crayfish out of the tank (if possible) would be a good idea, eh?

When I treat the pygmy sunfish tanks, the blackworms (lots of them) just seem to retreat into the substrate.