Hydrogen Peroxide: The Nuclear Option with Nuisance Algae

Use of hydrogen peroxide for algae control has been making the rounds lately and after a recent thread here by Brandon I thought I would give it a go. A couple rocks in my nano had some tenacious red slime algae left over from pre-doser days when my alk and pH were stuck in the basement. Brandon's great observations really put me at ease with this experiment, but I took some precautions. I decided to go with out-of-the-tank application and coupled it with a water change. I am happy to report that it worked as advertised without side-effects I can see days later. Details below.


Target application of hydrogen peroxide.

I started by manually removing as much of the red-slime algae as I could with a siphon hose during my water change routine. I then placed the rocks in my sink and pulled out the hydrogen peroxide. The 3% variety found at Target.

Then I took a clean unused hypodermic needle from a test kit and filled it with peroxide. The hypo is great for target application. (In the end though I felt that an I.V. bag with hose or something similar might work better for large areas.) That said, I then applied it across the algae areas on the rocks.

What was interesting about the rocks I used was that one was very porous (shown in pic above) and the other (in pic below) was very smooth. This quickly highlighted a challenge. The porous rock quickly absorbed the hydrogen peroxide before I could cover the algae with it. This rock took a lot more peroxide to cover than the smooth rock. It made me uncomfortable and I rinsed it thoroughly as I was paranoid about peroxide being left deep inside.

Application on the smooth rock was very easy and went quickly.

In all, I believe I filled up that needle about 5 or 6 times, so about 30ml of hydrogen peroxide was applied. I then let the rocks sit for a few minutes and then rinsed them off. For rinse water I had 1/2 gallon of ro/di water. I used it all on these two rocks. (Note: Many seem to use saltwater to rinse. I did not have extra saltwater made up and did not see the harm in using RO/DI so I went that route)

The porous rock went into the sump as I decided it was not needed in the display. After putting the smooth rock back in the display tank, I finished my water change removing 5 more gallons. I hovered the siphon around that smooth rock during this as a precaution in case there was still some peroxide on it.


Observations:

The very next day the red-slime algae had turned completely white in the thick area and a light green in the other areas.

By Day 2 (shown below) the algae that had turned light green was 50% gone completely. The thick stuff that had turned white was greatly reduced as well.


Day 2 showed rapid reduction in red-slime algae. In fact, it was gone.

I did take a glance at the skimmer on the night of day 2 and found it really interesting to see a reddish skimmate (shown below). I am curious to hear the speculation on why it is red. I should also note that the skimmer went nuts after I started the tank back up after the water change and peroxide application. I suspect the algae die-off has something to do with it and perhaps residual peroxide.


Red skimmate noted in skimmer.

The next day all fish and inverts acted normal and the fish ate readily. I did not note any odd behavior here.

Polyp extension is noted on all corals.


Mistake made:
During application I did fumble adjusting the needle once and accidentally squirted an SPS frag. Ugh. Although I rinsed it within 10 seconds, this frag now has a noticeable burn although it appears fine around the edges. I suspect it will come back, but time will tell. So, learn from my mistake, and be extra cautious around corals when applying peroxide.


Recommendations and final thoughts:

I am happy to report that the red-slime is gone and life in the tank appears completely normal. This write-up is only a few days out from application so this is by no means a conclusive test of hydrogen peroxide use for algae control and I will certainly follow up if anything adverse occurs. However, based on what I am observing so far, I am optimistic. Yet I feel it is way to early for me to recommend this for others.

I do wish to state if you have a new tank and you want to go this route to get rid of the nasty algae in your tank, I would recommend just riding it out. You are experiencing a cycle and peroxide may really mess with that. However, if you have a mature tank that is bouncing back from bumps like mine and this may be an option for the algae left over. I especially see this method being applied occasionally for nano owners like myself that do not have the option of a rabbit fish or tang for aggressive algae control.

That said, the long-term solution for algae-control should be to address the reasons that the algae is there in the first place.

In my case, I believe it was do to low alk/pH and poor water flow where the smooth rock used to be. I have raised the alk and rotated the rock. (Edit - I also started dosing kalk again and picked up the water changes.)

I hope these details and observations help others considering hydrogen peroxide application. If things continue to be positive from here I plan on actually adding some more corals to my aquarium and updating my dusty build thread soon.


Hope this helps with you...


matt

 

Congrats on it working out for you Matt
hopefully future updates will be equally positive

I think the reason many would use tank water to rinse would be to preserve the bacteria on the rock
but as you only did a small percentage of your total bio filter system I suspect it will not matter

 

Good point Steve - that makes sense. And thanks!

 

Nice write up Matt

 

Nice, any idea how this would work on GHA? I'm about to break my tank down and nuke everything over a nasty GHA invasion.


Also, aren't most of the bacterium in our rocks the same as in freshwater systems? I don't think the bacteria require salt... but I'm often wrong on tank matters

-Doug

 

You know Doug I am not 100% certain and that is why I said tank water
becuase even in freshwater you should rinse a bio filter in tank water rather than shock it with new water
so I assume principle would be same and rinsing a rock in old tank water that happens to be saline would be best bet for the bacteria?

 

Hi Doug - my hunch would be that it would nuke GHA too. Check out Brandon's thread I linked in the 1st post for leads on this.

matt

 

awesome to see someone else have luck with this I have used peroxide for dinos a couple of months ago but I dosed right into the tank. I did around 12 mL a day for a couple of weeks. Interestingly enough my zoanthids LOVED it. they turned a brighter color and opened up more than ever while I was dosing. I saw absolutely no ill effects on any acros or euphylias in my tank while dosing. I have heard it works well for hair algae as well but I don't have any so I can't comment on that.

 

It definitely works well for hair algae and other algaes as well. It just takes a longer exposure period if the species is thicker like calerpa or bubble algae.

We learned about this technique about a 2 years ago from Justin Credibel of Exotic Reef Imports where he was using it to rid the aquaculture system of nuisance algae.

The reason the zoanthids get brighter is because it probably kills the zooxanthellae in the coral since it is also an algae.

 

i'm gonna do this with my tank, thanks, Matt!