Dry Rock Acid bath or not to Acid bath

[Tropicaltone]

Hi Guys,

I've recently started a small 28g marine aquarium with all dead dry reef rock (looks a bit like fiji) and dry dead sand. Hoping this would start it of as clean and cheap as possible.
I washed my rock with a scrubbing brush and a hose then put them in the new tank with freshly mixed salt water. I got as much dirt off the rock as possible and it seemed fairly clean so I put in a barebottom tank to cure and cycle with a powerhead on (no lights or filtration on)

The next day I did a water test and the Ammonia has spiked to 2ppm, 0.25 Nitrite and phos .75. As I added nothing other than rock I am guess it has some decaying matter in the rock.

I tested again today and the Amonnia has dropped to 1ppm, Nitrite to 0.50, Nitrate to 20ppm and phos 1ppm.

So it looks like it's cycling nicely. My concern is the phos, would it be worth my while taking the rock out to acid bath them.....maybe in Critic Acid to reduce phos?

Tropicaltone

 

[mcgyvr]

Lanthanum Chloride is typically used for phosphate problems like that..
You can also use muriatic acid to burn off layers in the rock too and hope that works for you..

IMO its a small amount.. I 'd trash it and buy new rock..
You can pick up enough for your tank here for $73 shipped and its clean/phosphate free and ready to go..
https://www.reefcleaners.org/aquarium-store/rock
Not worth the time IMO to try to save such a little amount..
But thats me..

 

[Tropicaltone]

Thanks, what if I did a mild acid bath then run Rowaphos in an external filter to remove the phosphate?

 

[Tropicaltone]

I would but I am in the UK and can only get regular Dry reef rock.

 

[mcgyvr]

Thanks, what if I did a mild acid bath then run Rowaphos in an external filter to remove the phosphate?

Granular Ferric Oxide (rowaphos, phosban, etc....) all work but typically cost more than lanthanum chloride..
And I'd bet it would cost more than finding another source of clean rock too..
Quick google search found this..
http://www.marineaquatics.co.uk/shop/caribsea-life-rock.html

 

[Tropicaltone]

Thanks for the link. It is nice and better than my rock but would cost me nearly £90 ($114) and waste the £40 I have already spent. I am trying to do this inexpensively. I bought the rock from here https://www.iquaticsonline.co.uk/dried-reef-rock/dried-reef-rock-10kg.html they do say it needs to be soaked for a while.

 

[Tropicaltone]

Surely the point of soaking and curing dry rock is to breakdown the dead life forms in the rock and afterwards shouldn't leach phosphates or Ammonia?

 

[mcgyvr]

Surely the point of soaking and curing dry rock is to breakdown the dead life forms in the rock and afterwards shouldn't leach phosphates or Ammonia?

Yes curing rock is intended to "get the nasty" out so you don't put that into your tank..

 

[Tropicaltone]

So I could take it out, acid bath it with citric acid then rinse then 1:10 bleach for 24hrs then rinse and leave to cure in a bucket of saltwater with pump for about a month or so?

 

[sfdan]

"Leaching ammonia" isn't a thing, or a bad thing. There is dead stuff on the rock that will decay and produce ammonia, which the bacteria in your tank will handle. This is a one time thing. Not a problem.

Phosphate on the other hand is bound in the rock itself. The rock is like a sponge and will release phosphate when the levels in the water are less than what is bound in the outer layer of the rock, and will absorb it in the opposite condition. This could last months depending on how much phosphate is bound in there. An acid bath tries to dissolve the outer layers of the rock, which have the most phosphate bound. GFO or Lanthanum Chloride will remove phosphate from the water column, after it has leached out from the rock. Then after the phosphate is removed from the water column, more phosphate will leach out of the rock to find equilibrium, a process which can go on for a while.

I think it took 3-4 weeks of daily dosing of Lanthanum Chloride to get vats of my dry rock down to acceptable levels of phosphate.

 

[mattgumaer]

BRS did a video about preparing rock, including bleaching versus acid, versus bleaching + acid. Their conclusion seemed to be that bleaching was likely the best route, with any marginal increased benefit of using acid not being worth the risk.

I'm bleaching some rock right now, relying on their conclusions. My rock has been in a tub of heated, circulating RO water + bleach for about 4 days now. I've got about 20 gallons of water to 2 gallons of regular strength bleach. To soon to offer any personal anecdotal opinions on results though......

Good luck.

Matt

 

[Tropicaltone]

Thanks Matt I have seen the BRS video also. That was my intention as they say using acid and bleach to be the best possible result. I didn't want to use dangerous muratic acid instead I would use a safer Citric Acid then a bleach soak.

 

[reefgeezer]

There are many ways to start a tank with dry rock. The two issues to worry about are: 1) Ammonia spikes caused decay of dried organic materials trapped inside the rock; and 2) Phosphates leaching from the rock into the DT water.

I started my tank with dry rock and learned some hard lessons. To keep it short here is the process I would use if I were to do it again. The goal would be to produce rock that was cycled and phosphate free.

1. Set up a dark vat full of cheap ASW with a power head in it somewhere where temps are reasonable.
2. Do a quick muratic acid bath (or longer with vinegar) on the rock & rinse with a power washer. This is simply to remove the phosphates & organics bound to the outer surfaces.
3. Place the rock in the vat and leave it alone for a few days.
4. Test for phosphates & ammonia with good kits.
5. If ammonia is up, that's ok, the rock will cycle. If not add a little ammonium chloride of suitable ammonia cleaning solution to kick start the cycle.
6. If phosphate is elevated, begin adding Lanthanum Chloride to the vat daily until phosphates no longer show elevated. Once they stay at 0, wait a few days & test again to see if there is some minor leaching. A little is OK, but I'd try to keep it like .01 ppm in 2-3 days.
7. While treating the bound phosphates, monitor the cycle and add ammonia or ghost feed as needed. It may take a few weeks or more to get the phosphates out. The cycle may actually complete first.

Water changes can be done during this process if you want. It may speed up the phosphate leaching process a little. Once the process is complete, the rock will still need some cycling once you put it in the DT, but the time period will be short.

 

[Tropicaltone]

Thanks John, that is sort of what I had in mind. I will also soak in a 10% bleach solution overnight

 

[reefgeezer]

I have been a fan of bleach in the past, but in this case, you want the organics in the rock to feed the cycle. I'd skip the bleach.

 

[Tropicaltone]

What do you mean by ASW?

 

[reefgeezer]

What do you mean by ASW?

Sorry... "Artificial Sea Water" most just call salt mix like Instant Ocean. Cheap stuff is fine.

 

[Tropicaltone]

Matt, how long do you plan to soak your rock in a bleach mix for?

 

[mattgumaer]

Matt, how long do you plan to soak your rock in a bleach mix for?

My initial plan was a week but I un-bleached last night, so about 4.5 days. This is mostly because I'm anxious to make progress on the tank and no one in the house was particularly fond of the bleach smell in the basement.

I'm basically using dechlorinator now to remove bleach. I'll probably pull the rock tonight and let it dry out, then, once dry, back into some circulating salt water and do some testing to see where things stand. I'm not too concerned about phosphate but, maybe that's because it hasn't bitten me in the past. Over time, I've also come to the belief, right or wrong, that a goal of ultra low nutrients may be counterproductive, particularly if you have a lot of potentially fast growing coral. However, I'm far from an expert.

Matt