Bleach vs Acid

[bertoni]

The sand will be hard to clean because it has so much surface area and it's harder to get the acid to all those surfaces. I'd just pitch it.

 

[Bpb]

I'm going to be attempting this method this week. Read the whole thread and just want to clarify a few things.

First...have an established tank, with about 50 lbs of holy rock as my bottom layer rock that is allowing alot of detritus to collect under it, likely has a boatload of phosphate it is leeching, and lastly, is ugly and providing virtually zero biological filtration value. I've bought some comparably sized liverock from someone that broke down their FOWLR. It had a bit of cyano and hair algae on it, but the shapes and porosity are killer. I bleached it a while back and have been trying to cycle it in a tub in the garage, but the temperature swings are killing the cycle every time it gets cold. Confirmed with tests.

After reading this I'm sure it's got a bit of phosphate since it came from an FOWLR with some algae attached. Either at I wanna be sure.

Questions...can I use tap water as my acid bath for these rocks? Or will that possibly introduce and bind more phosphate or metals to the rock? I'd rather not waste another 30 gallons of ROdi if tap will suffice. I'll DEFINITELY use clean ROdi as the rinse water...

Next question...I had planned on curing the rock remotely before adding it, but until the climate gets stable it may be a couple months before I can START curing it. Is it going to give any negative effects if I just add it directly to the mature tank? It's not totm material, but I've got enough sps and lps that I'm happy about that id rather not screw something up!

Should I still cure it remotely? Or is it safe to add straight away once it's been acid washed and rinsed?

 

[Bpb]

By replacing the Texas holy rock at the bottom, I am hoping to accomplish a more pleasing looking tank with higher-quality rock. I have already bleached the rock to get rid of the algae and dead organics, I am trying to accomplish a reduction of bound phosphate by the acid bath.

 

[bertoni]

The acid treatment likely will be okay even with tap water. After treatment, it might be safe to add it to the tank as is, but it's hard to be sure. It might still have a fair amount of organic debris or even phosphate remaining in it. I would cure it separately, personally, but I am risk-averse in situations like this.

 

[Gools]

I have a couple hundred pounds of rock that I have had in storage for the last 2+ years, just want to give it a good clean and put it in my new tank. Just wondering if just doing the bleach method would be good enough to give the rocks a good clean before adding to my new system, or should I also do the acid treatment to?

 

[bheron]

It all depends on what you're looking to do, as each method accomplishes something different.

1) Bleach - will kill all organic material, meaning all alive or previously alive and now dea matter.

2) Acid - will burn away the outer layer of the rock in an attempt to remove phosphate that may be deposited there.

At minimum the bleach is a great idea, just know you'll have completely dead rock at this point.

I've done this a few times so let me know if you have more questions.

 

[dkeller_nc]

I have a couple hundred pounds of rock that I have had in storage for the last 2+ years, just want to give it a good clean and put it in my new tank. Just wondering if just doing the bleach method would be good enough to give the rocks a good clean before adding to my new system, or should I also do the acid treatment to?

Everything organic in nature on your rock is long, long dead, so you've no real reason to bleach it. If you wished to hydrolyze any dead material without affecting the rock structure, a fairly dilute solution of sodium hydroxide (about 0.02M) would do it. But if you're going to acid wash it anyway, any organic material adhering to the rock will likely come away in the rinses since the outer layer of the rock will be removed.

 

[bheron]

Even though its dead isnt it still considered waste and harmful to a tank? I would think you dont want dead organic material on those rocks?

 

[dkeller_nc]

Even though its dead isnt it still considered waste and harmful to a tank? I would think you dont want dead organic material on those rocks?

Yes, but bleach, at least at the concentration sold to consumers, won't do much of anything to that dead organic matter. It has a little bit of sodium hydroxide in it as a stabilizer, which will hydrolyze proteins in dead organic matter, and saponify lipids (turn them to water-soluble soap, basically). But the amount of sodium hydroxide in bleach is quite low. You'll get a much bigger effect by just mixing up some sodium hydroxide from pure lye (which you can buy at the grocery or home store).

 

[bheron]

wow had no idea. and ive been through this a bunch of times! very interesting - I thought the bleach "oxidizes" any and all organic matter, dead or alive. My rock always seems so clean from what I can tell.

Ok, so love this hobby b/c always learning

dkeller, I use sodium hydroxide in the form of the roebic crystal drain opener. I recently learned you can get it much cheaper in pure forms. You say "a fairly dilute solution of sodium hydroxide (about 0.02M)". Can you dumb that down a bit ? How much sodium hydroxide to, say, 10 gallons of water?

And that will surely kill all organics, dead or alive?

 

[dkeller_nc]

wow had no idea. and ive been through this a bunch of times! very interesting - I thought the bleach "oxidizes" any and all organic matter, dead or alive. My rock always seems so clean from what I can tell.

Ok, so love this hobby b/c always learning

dkeller, I use sodium hydroxide in the form of the roebic crystal drain opener. I recently learned you can get it much cheaper in pure forms. You say "a fairly dilute solution of sodium hydroxide (about 0.02M)". Can you dumb that down a bit ? How much sodium hydroxide to, say, 10 gallons of water?

And that will surely kill all organics, dead or alive?

You are correct that bleach oxidizes organics, but the issue is that it oxidizes some organics. From a chemistry perspective, what you're trying to do is hydrolyze proteins to break them down into soluble compounds, and for lipids/fats, saponify them into a water-soluble form. There are quite a lot of ways to do this, but one of the cheapest/easiest way is to use sodium hydroxide and wait a few days.

To make a 0.02N (or 0.02M, it's the same with NaOH), you need to dissolve 0.08 g of NaOH per liter of water. For 10 gallons of water, that works out to 37.9L*0.08g = 3 grams.

If you need to do this by volume measurement, that's about 1/2 of a teaspoon.

Having said this and done the calculations, I realize I made a decimal point mistake in my previous post - I would use 0.2M NaOH, not 0.02M NaOH. So instead of 1/2 teaspoon of lye in 10 gallons, you need 5 teaspoons in 10 gallons.

You can let this mixture stew for several days with your rock - it won't dissolve the rock itself, nor make any hazardous fumes. Though realize that sodium hydroxide will definitely cause a chemical burn to your skin - wear gloves and splash protection for your eyes.

Once done, you can neutralize the sodium hydroxide with vinegar. You can also do it with hydrochloric acid, but if you do so, be very cautious - the neutralization reaction will be violent.

 

[cjcolvin]

If you have access to a pool supply store the liquid chlorine they have normally ranges in 10-20% range and will also accomplish what dkeller has suggested just a tad bit easier albeit a little bit more expensive. I have had success with using this method. Now it won't get rid of everything but just about.

 

[bheron]

You are correct that bleach oxidizes organics, but the issue is that it oxidizes some organics. From a chemistry perspective, what you're trying to do is hydrolyze proteins to break them down into soluble compounds, and for lipids/fats, saponify them into a water-soluble form. There are quite a lot of ways to do this, but one of the cheapest/easiest way is to use sodium hydroxide and wait a few days.

To make a 0.02N (or 0.02M, it's the same with NaOH), you need to dissolve 0.08 g of NaOH per liter of water. For 10 gallons of water, that works out to 37.9L*0.08g = 3 grams.

If you need to do this by volume measurement, that's about 1/2 of a teaspoon.

Having said this and done the calculations, I realize I made a decimal point mistake in my previous post - I would use 0.2M NaOH, not 0.02M NaOH. So instead of 1/2 teaspoon of lye in 10 gallons, you need 5 teaspoons in 10 gallons.

You can let this mixture stew for several days with your rock - it won't dissolve the rock itself, nor make any hazardous fumes. Though realize that sodium hydroxide will definitely cause a chemical burn to your skin - wear gloves and splash protection for your eyes.

Once done, you can neutralize the sodium hydroxide with vinegar. You can also do it with hydrochloric acid, but if you do so, be very cautious - the neutralization reaction will be violent.

Dkeller - this is great info. thanks! just when I thought I was well-versed on this topic...I find out I'm pretty off. Ok, I'm going to modify my approach with this latest batch. So use "0.2M NaOH", which means with my rock sitting in about 40 gallons of water use 20 teaspoons?

Also, re: "hydrolyze proteins to break them down into soluble compounds, and for lipids/fats, saponify them into a water-soluble for"

- so what does that mean? soluble compounds are safe to transfer back into the tank? or does that mean they'll be washed away with the "water" during the rinse process.

I find this very interesting so thanks for the time.

 

[blanden.adam]

dkeller -- I don't disagree that using a more concentrated of sodium hydroxide is fine, but I'm wondering why you don't believe the sodium hypochlorite in bleach to be of value. It is a strong oxidizer afterall and makes the rock look oh so pretty and white . I've also found that when I've treated rock with bleach beforehand, I get a lot less "gunk" hanging onto the rock after the subsequent muriatic acid bath.

 

[bheron]

Got a related question (maybe a seperate thread if needed):

How can I clean the sand from a DSB? In essence want to strip it of all organic material so it can be re-used in a brand new tank, not carrying over any potential waste and/or disease.

My non-chemist brain is thinking acid would begin to disintegrate the sand??

thoughts?

 

[Bpb]

I wouldn't try it on sand. When I acid dipped my rock it dissolved about 25% of its overall mass within 20 minutes. Since sand has so much surface area I'd expect it would dissolve most of it completely. To reuse sand I always just fill buckets half way and run the water hose in them really agitating it until the water runs totally clear, then I'll fill the buckets with RODI water and store them for a few days like that to rinse the sand. I could be off mark here, but since 0 tds water is highly reactive, I feel like a lot of the tap impurities and such would diffuse from the sand into the RODI. Pour off the water when ready to use and add sand however you like to. I've been changing the sandbed out incrementally on my tank that is mature and running. I'll siphoned out old sand in one section down to the glass, put a PVC pipe in the water with a funnel at the top and add the sand in 2 cups at a time. Slow process but zero water nastiness. All the organics are removed via siphoning, it's a small enough amount that I can catch and keep snails and stuff, and adding the new sand this way results in literally zero cloudiness or sandstorms.

 

[brandon429]

bleach is more than enough to accomplish the sand cleaning. 35% P would do it well also... i got a quart of that rocket fuel in the fridge for needed days.

 

[bertoni]

Bleach should help remove organics from sand. If the sand has adsorbed a lot of phosphate, though, the bleach won't help. You could test that by cleaning the sand and then soaking a bit in RO/DI water.

 

[bheron]

great thanks! I'l start a new thread if/when I decide to document the process.

 

[l8_apex_it]

I was a bit to eager to start the process today and used tap water for the first bleach round. I imagine if I do the next round of bleach with RO and a powerhead and then complete the acid bath and rinses all with RO water I should be fine.?