Technique for Spot-Treating Algae In Tank (unless it's dumb) NaOH+H2O2

[taricha]

(Edit: after trying it, Garf's suggestion - posts 4,5,6 - is better. I'd use Sodium Hydroxide denser than saltwater + Calcium Hydroxide.)
I looked for a few different things to kill hunks of algae in a tank without having to pull the rock out and that might be less work/more effective than scrubbing or tweezering.
I was thinking about techniques that would be highly lethal locally in the water, but totally harmless when diluted to the tank volume.

Boiling water in squeeze bottles: modestly effective, too much risk for accidental burns (shudder to think about what spilling boiling water on tank glass would do) etc.
Peroxide: immediately floats up and not enough potency on the surface.
Freshwater: only very few nuisances killed quickly by this.

But I found one that I like. Seems convenient, quick, good local lethality, low risk (I think), no large dilute effects.

Sodium Hydroxide solution and Hydrogen peroxide mix.
Posted here in the chem forum for somebody to shoot me down if this is dumb or pointless for some unanticipated reason.
I take 5Molar NaOH and mix 1:1 with 3% drugstore H2O2 in a test tube. For my 60 gal system I am doing 1 mL of each. If I did the math right, this amount of NaOH only raises dKH ~0.02, and the 1mL of 3% H2O2 doesn't seem to cause peroxide-sensitive corals to react.
Turn off all tank pumps and flow.
Use pipette to put small amount of this on the GHA or whatever.

The mix has a greater density than the tank water, so it stays put/falls down onto the nuisance patch. It also immediately precipitates the saltwater around, forming gloopy clumps. The gloopy precipitate seems to hold some of the H2O2 inside it, as bubbles continuously emerge up from the blobs. I leave the pumps and flow off for 20 minutes. Apparently the peroxide sticks around the surface it's applied to, as it continues bubbling for the entire 20 minutes the pumps are off.

Then turn the pumps back on and the precipitate blows away and redissolves to nothing. There's nothing left behind. The algae pigments are immediately changed in color indicating deep chemical damage. Sticking on the surface for that length of time also apparently kills "roots" or portions of algae in the porous surface. Nothing regrows from below the surface, the surface bleaches white until it's recolonized over days and weeks.

It's possible that the peroxide is entirely irrelevant. Concentrated NaOH is plenty to kill most of this stuff - but the peroxide gives very satisfying bubbles, and I suppose there could be some things that the combination is more effective against. Anecdotally, some herbivores seem attracted to the dead algae after it gets hit by peroxide.

Here's a few pics of applications around my tank. Follow-up pics around a week later.

I've also used it to kill off palys and aiptasia as well.

This was a Paly rock that I cleared by manual cutting and then a few rounds of the NaOH+H2O2 pipette.

 

[Garf]

I looked for a few different things to kill hunks of algae in a tank without having to pull the rock out and that might be less work/more effective than scrubbing or tweezering.
I was thinking about techniques that would be highly lethal locally in the water, but totally harmless when diluted to the tank volume.

Boiling water in squeeze bottles: modestly effective, too much risk for accidental burns (shudder to think about what spilling boiling water on tank glass would do) etc.
Peroxide: immediately floats up and not enough potency on the surface.
Freshwater: only very few nuisances killed quickly by this.

But I found one that I like. Seems convenient, quick, good local lethality, low risk (I think), no large dilute effects.

Sodium Hydroxide solution and Hydrogen peroxide mix.
Posted here in the chem forum for somebody to shoot me down if this is dumb or pointless for some unanticipated reason.
I take 5Molar NaOH and mix 1:1 with 3% drugstore H2O2 in a test tube. For my 60 gal system I am doing 1 mL of each. If I did the math right, this amount of NaOH only raises dKH ~0.02, and the 1mL of 3% H2O2 doesn't seem to cause peroxide-sensitive corals to react.
Turn off all tank pumps and flow.
Use pipette to put small amount of this on the GHA or whatever.

The mix has a greater density than the tank water, so it stays put/falls down onto the nuisance patch. It also immediately precipitates the saltwater around, forming gloopy clumps. The gloopy precipitate seems to hold some of the H2O2 inside it, as bubbles continuously emerge up from the blobs. I leave the pumps and flow off for 20 minutes. Apparently the peroxide sticks around the surface it's applied to, as it continues bubbling for the entire 20 minutes the pumps are off.

Then turn the pumps back on and the precipitate blows away and redissolves to nothing. There's nothing left behind. The algae pigments are immediately changed in color indicating deep chemical damage. Sticking on the surface for that length of time also apparently kills "roots" or portions of algae in the porous surface. Nothing regrows from below the surface, the surface bleaches white until it's recolonized over days and weeks.

It's possible that the peroxide is entirely irrelevant. Concentrated NaOH is plenty to kill most of this stuff - but the peroxide gives very satisfying bubbles, and I suppose there could be some things that the combination is more effective against. Anecdotally, some herbivores seem attracted to the dead algae after it gets hit by peroxide.

Here's a few pics of applications around my tank. Follow-up pics around a week later.

I've also used it to kill off palys and aiptasia as well.

This was a Paly rock that I cleared by manual cutting and then a few rounds of the NaOH+H2O2 pipette.

Any reason you decided sodium hydroxide mixed with calcium hydroxide wasn’t good enough? LOL. Just for the bubbles?

 

[taricha]

Any reason you decided sodium hydroxide mixed with calcium hydroxide wasn’t good enough? LOL. Just for the bubbles?

Is that a thing people do?
And yes, the bubbles are satisfying.

 

[Garf]

Is that a thing people do?
And yes, the bubbles are satisfying.

I do on occasion in the wife’s tank. Used it in my current tank early on in its life to get rid of bryopsis hiding in crevices. Used to use just calcium hydroxide paste years ago, didn’t quite have the oomph! I guessed that F Aiptasia is just kalk and sodium hydroxide, so tried it and it works great, on everything.

 

[taricha]

Any reason you decided sodium hydroxide mixed with calcium hydroxide wasn’t good enough? LOL. Just for the bubbles?

I do on occasion in the wife’s tank. Used it in my current tank early on in its life to get rid of bryopsis hiding in crevices. Used to use just calcium hydroxide paste years ago, didn’t quite have the oomph! I guessed that F Aiptasia is just kalk and sodium hydroxide, so tried it and it works great, on everything.

I gave it a try, and I think I might like @Garf solution better. NaOH (strong enough to be denser than saltwater) + a bit of calcium hydroxide seems to have a nice combination of punch (discolors algae pigments quickly) and stays in place easier thanks to the solids.

I'll update in a few days.

 

[areefer01]

I like to grab a hose, create a siphon, clamp end in a filter sock in the sump. Play some calming music, ladder, reach in, grab a pinch, gently pull while opening the hose so it gets sucked in. I work in small batches. I'm just getting the longer pieces so what is left the herbieviors will clear out. Mine seem to go after the freshly mowed, short, algae and leave the long wispy stuff alone. I guess they don't like Fabio's golden long locks of hair...

To your point I have read here and elsewhere of hobbyist doing what you noted with success.

 

[Miami Reef]

Following.

 

[Dburr1014]

I looked for a few different things to kill hunks of algae in a tank without having to pull the rock out and that might be less work/more effective than scrubbing or tweezering.
I was thinking about techniques that would be highly lethal locally in the water, but totally harmless when diluted to the tank volume.

Boiling water in squeeze bottles: modestly effective, too much risk for accidental burns (shudder to think about what spilling boiling water on tank glass would do) etc.
Peroxide: immediately floats up and not enough potency on the surface.
Freshwater: only very few nuisances killed quickly by this.

But I found one that I like. Seems convenient, quick, good local lethality, low risk (I think), no large dilute effects.

Sodium Hydroxide solution and Hydrogen peroxide mix.
Posted here in the chem forum for somebody to shoot me down if this is dumb or pointless for some unanticipated reason.
I take 5Molar NaOH and mix 1:1 with 3% drugstore H2O2 in a test tube. For my 60 gal system I am doing 1 mL of each. If I did the math right, this amount of NaOH only raises dKH ~0.02, and the 1mL of 3% H2O2 doesn't seem to cause peroxide-sensitive corals to react.
Turn off all tank pumps and flow.
Use pipette to put small amount of this on the GHA or whatever.

The mix has a greater density than the tank water, so it stays put/falls down onto the nuisance patch. It also immediately precipitates the saltwater around, forming gloopy clumps. The gloopy precipitate seems to hold some of the H2O2 inside it, as bubbles continuously emerge up from the blobs. I leave the pumps and flow off for 20 minutes. Apparently the peroxide sticks around the surface it's applied to, as it continues bubbling for the entire 20 minutes the pumps are off.

Then turn the pumps back on and the precipitate blows away and redissolves to nothing. There's nothing left behind. The algae pigments are immediately changed in color indicating deep chemical damage. Sticking on the surface for that length of time also apparently kills "roots" or portions of algae in the porous surface. Nothing regrows from below the surface, the surface bleaches white until it's recolonized over days and weeks.

It's possible that the peroxide is entirely irrelevant. Concentrated NaOH is plenty to kill most of this stuff - but the peroxide gives very satisfying bubbles, and I suppose there could be some things that the combination is more effective against. Anecdotally, some herbivores seem attracted to the dead algae after it gets hit by peroxide.

Here's a few pics of applications around my tank. Follow-up pics around a week later.

I've also used it to kill off palys and aiptasia as well.

This was a Paly rock that I cleared by manual cutting and then a few rounds of the NaOH+H2O2 pipette.

I may have to try this. I have a couple aptaisia rearing there ugly heads.
Must work on blue clove too. Hmmmm.

 

[Dburr1014]

I do on occasion in the wife’s tank. Used it in my current tank early on in its life to get rid of bryopsis hiding in crevices. Used to use just calcium hydroxide paste years ago, didn’t quite have the oomph! I guessed that F Aiptasia is just kalk and sodium hydroxide, so tried it and it works great, on everything.

Really, do you think or know that is what F-aptaisia is?

 

[taricha]

@areefer01 I've done similar a few times and razed the algae down to the rock, and when the new shoots came out, my herbivores (all the most respected herbivores) just still wouldn't touch it. I apparently grow the worst tasting algae on earth.
Anyway.
This amount of work is small enough that I'll actually do it once a week or so:
1mL of my NaOH, 1mL of H2O2 (or Garf's possible improvement - tiny scoop of Kalk) then turn off the switch for my pumps and pipette on the spots I don't like.
I've never vacuumed my sandbed. I hate doing the dishes

Must work on blue clove too.

Did it on strawberry nems, a paly, an aiptasia, and a few out of place mushrooms today. Not sure about cloves. I should try it on Green Star Polyp. If anything can shrug it off, maybe it's GSP.

Really, do you think or know that is what F-aptaisia is?

F-aiptasia also contains something that allows it to form a rigid crust over the target. It didn't look to me like kalk + NaOH gets you that.

 

[Garf]

F-aiptasia also contains something that allows it to form a rigid crust over the target. It didn't look to me like kalk + NaOH gets you that.

If you use more kalk a presumably, magnesium hydroxide shell, developes and forms a crust, leave flow off for 1.5 hrs.

Really, do you think or know that is what F-aptaisia is?

Nope, just a guess. But it works.

18 months ago I attacked the left hand side of this bryopsis infested rock with it (I know the pic is a bit rubbish, sorry). Almost immediately, coralline took hold. I like a good guess, so I guessed this was because magnesium had been laid down onto the rock. Even where the mixture dribbled off the rock was quickly corallined over.

 

[taricha]

If you use more kalk a presumably, magnesium hydroxide shell, developes and forms a crust

ooh, interesting!

leave flow off for 1.5 hrs.

no thank you.

 

[Garf]

no thank you.

You worry too much, lol

 

[Dburr1014]

If you use more kalk a presumably, magnesium hydroxide shell, developes and forms a crust, leave flow off for 1.5 hrs.

Nope, just a guess. But it works.

18 months ago I attacked the left hand side of this bryopsis infested rock with it (I know the pic is a bit rubbish, sorry). Almost immediately, coralline took hold. I like a good guess, so I guessed this was because magnesium had been laid down onto the rock. Even where the mixture dribbled off the rock was quickly corallined over.

Son of a friggin gun.
Google search says milk of Magnesia is magnesium hydroxide. Is this what they put in F-aptaisia? It's got that "color".
LOL if it's true.

 

[trainbob]

I checked Amazon today for sodium hydroxide and was stunned to find out it is lye . Are you actually adding lye to your reef tank. Plus I assume you are using the liquid form

 

[Dburr1014]

I checked Amazon today for sodium hydroxide and was stunned to find out it is lye . Are you actually adding lye to your reef tank. Plus I assume you are using the liquid form

Randy holmes farley has a article on adding lye as alkalinity.
Yes, that's what it is.

Thread 'Second New DIY Two Part Recipe with Higher pH Boost' https://www.reef2reef.com/threads/second-new-diy-two-part-recipe-with-higher-ph-boost.357080/

 

[trainbob]

Thanks think I will wait and see how it works out

 

[taricha]

(That reminds me, If you don't have a bottled NaOH solution strong enough, a small pellet of NaOH in a couple of mL of water also seems to have the necessary density greater than saltwater. )

 

[taricha]

After trying on a few more targets and checking the next day, yes I'm sure I like @Garf solution better: NaOH with a little Ca(OH)2...

I gave it a try, and I think I might like @Garf solution better. NaOH (strong enough to be denser than saltwater) + a bit of calcium hydroxide seems to have a nice combination of punch (discolors algae pigments quickly) and stays in place easier thanks to the solids.

The solids from kalk are especially helpful in making the result stay better on anemones, polyps etc. And it seems just as potent on algae as what I was originally doing.

 

[McPuff]

Here's a trick... how do I get rid of aiptasia that are growing in the midst of zoanthids that I don't want to kill? Sounds like the methods herein would kill both. Probably just have to use biological methods, huh? I do have a filefish but really afraid to add him because the triggers are messing attack dogs when I add something new. :0( Thinking that berghia may be my only good solution.