# I am new at this. How often can H2O2 be used to kill algae?



## Sgtreef (Jul 4, 2004)

Topic says it all.
How often can H2O2 be used to kill Algae.
Can it be used two weeks in a row before water change?
Thanks.
PS I know saltawater Reef tanks pretty good.

Jeff


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## Daemonfly (Mar 21, 2004)

It usually depends on what plants you have, as some are a lot more sensitive. I know for a fact that it can very easily kill off riccia, while other plants do fine.

I researched it a bit and came up with the following formula:

Hearty plant only, no fish - 1oz per 5g
Not as hearty and/or with fish - 1oz per 12g
Sensitive plants & fish - 1oz per 20g. Otos, snails & shrimp, this might even be too much for riccia.

If you're not sure, I'd start with 1/2oz per 20g and see how all your plants respond, then work the dose up. Don't rely on it as an overall cure for algae, but it works to get rid of _some_ types of algae quicky, then you can work to get your nutrients in balance for long-term results.

It worked great to weaken my BGA, then a full dosing of Maracyn finished it off completely, while either of them failed when used by themselves.

Disclaimer: I'm no expert on it


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## Sgtreef (Jul 4, 2004)

Thanks for the answer Dragonfly.
I guess I will hit the old Piranaha tank again. :shock:


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## anonapersona (Mar 11, 2004)

*Caution*

This can kill fish, so err on the side of caution. I would not exceed 5ml/10 gallon. Actually I'd stop way short of that.

I've used H2O2 in a syringe at 1ml at a time to kill BBA. I stopped at 2 spots per day, 2 ml total. The 1/2" area hit would bubble away, and the areas near would die back and be attacked by shrimp. I would hit again several days later, I read in other sources that the effect of H2O2 can be in the tank for 2 or 3 days, so I'd wait that long to insure fish safety.

I read that consistent CO2 is what really does the trick on BBA, though.


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## Bert H (Mar 2, 2004)

Jeff, if I were you, I'd be more concerned about why I have the algae, especially if it is persistant. (You mention 2 treatments in a short time period) Make sure your lighting, carbon source and fert regime are in balance and it will go a long way towards keeping algae at bay.


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## gpodio (Feb 4, 2004)

*Re: Caution*



anonapersona said:


> This can kill fish, so err on the side of caution. I would not exceed 5ml/10 gallon. Actually I'd stop way short of that


I've safely gone up to 20ml/10 gallons without any problems to fish or snails. Hornwart, riccia and other non rooted plants do have problems however, if you can, remove them prior to treating. For BBA, spot treatment works best, for other forms of algae whole tank treatment is often easier. Obviously as others said, it's not a solution to an algae problem, just an aid in cleaning it up. Work on solving the source of the algae as it will only come back if you don't.

Here's more info for you:
http://www.gpodio.com/h2o2.asp

Hope that helps
Giancarlo Podio


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## Sgtreef (Jul 4, 2004)

Thanks to all that have answered.
Okay I am starting a new post to put all the figures in.
Thanks again.
:wink:


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## Gomer (Feb 2, 2004)

I used 4oz/30g to kill off massive staghorn. I didn't loose any thing in that tank
(emerald eye rasboras, otos, SAE, cherry shrimp (that I could tell), amano shrimp (that I could tell), rams horn (that I could tell), crypt lucens, crypt retrospiralis, marsilea minuta).


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