Live rock cooking help

[makana]

I have some rock that I have been cooking in a tub for 8 weeks now. Every week the nitrate is 15 when I test before the w/c. There is nothing coming off of or out of the rocks as far as detrius.

Should I just keep going? Will this eventually stop? Is it possible that the bacteria in the rock that deals with nitrate is gone? Would I be better off not doing the w/c to let the bacteria that feed off nitrate rebuild if that is the case?

[gregzz4]

Yup, just keep going and it will eventually go away
If you'd like to see this, test your tub water soon after the change, so you see some results
Swish/rinse the rocks in the old water before your WC

When I cooked mine, I did 100% changes weekly and it took about 3 months to go from 1.5 NO3 and 0.5 PO4 to zero on both

You're not hurting any significant levels of bacteria by changing the water as they reside in the rock, not the water column

The bacteria that feed on ammonia, nitrite and nitrate will always be there, and their numbers will rise and fall with the levels, so no worries about them not being present

What kit are you using for nitrates, and how old is it ?
Are you testing for phosphates ?
Are you using a heater and powerhead in your tub ?
Do you have something over the tub to block light ?

[makana]

The rock is in a rubermaid tub with the lid on but not sealed. There is a heater and a mj1200 in the tub. I use api test kits, opened a new one a couple of weeks ago. I havn't tested for phosphates yet, was waiting for a zero reading on nitrates.

Its good to know it took you 3 months. I was expecting about two months so I was starting to wonder what was going on.

[gregzz4]

Sounds like you're doing it all well
I also used a MJ with the lid slightly open, and used the airline with the little ball valve to add some air to the tub for gas exchange. Not sure if it made a difference, but I'm sure it didn't hurt

You probably should be testing for phosphates as well
Seeing nitrates drop to zero will give you an indication of when the rock is finished cycling, but you want to see and end to PO4 leaching as well if you don't want any nuisance algae in your DT

Are you using RO water ?
Have you read Myka's write-up on cooking (http://www.canreef.com/vbulletin/showthread.php?t=44859) ?

[makana]

Ro/di water. It has been a while but i have read Myaka's guide along with most of the guides out there. For some reason I was expecting that the end of the detrius being pushed out of the rock would be the end of the cooking. I was surprised to see the nitrate issue. As far as I know live rock can't store or leech nitrate so I don't really understand where the nitrate is coming from. Its nice to know it is normal but it would help if I had some idea of where the nitrates are coming from in this situation.

[intarsiabox]

Nitrates are from the organic material on the rock decomposing. Having the exact same reading after 8 weeks and doing weekly water changes is possible but it could also be that you have a bad test kit. Try testing your ro water with the kit, it should not have any reading what so ever.

[makana]

I had the same results with the old test kit, new test kit is only two weeks old.

This week I actually tested my ro/di water and tested it again after mixing my salt for 24 hours for doing the w/c on my display last night. Both read 0.

I just tested phosphate in the cooking tub to be zero with a hagen and api test kit.

What I don't understand is that if there is organic matter being turned into nitrate, should the rock not be spitting out detrius?

[makana]

Okay, I just checked nitrate with an older hagen test kit and it reads 20.

[intarsiabox]

The solution to nitrate is dilution. How much water are changing each week? You may have to do a 100% water change and then start doing daily water changes for awhile. After a week of this check it again. Sometimes it just takes awhile but it will eventually work out for you.

[makana]

100% w/c every week for the last 8 weeks

[gregzz4]

I don't hold much faith in hagen test kits, and I haven't had good luck with api
You may get better results from salifert, red sea or elos

[makana]

I think with 3 seperate test kits all giving my the same results its safe to say the nitrates go from 0 to 15ppm in 7 days.

Another week has gone by with the same results. I would have thought by now that I would at least be seeing a reduction in the amount of nitrate I am reading.

Any other suggestions?

[gregzz4]

Other than blasting the rock in your tub with a decent powerhead, and rinsing/swishing it really well during your WCs, I think you'll just have to wait it out

[ChefFish]

Be patient, it took me 7 months to "cook" my live rock from my previous crashed tank. Keep doing your water changes and testing & you will get there.

[makana]

18 weeks and counting. Still no changes. The rock doesn't appear to bed purging any detrius and nitrates climb to 15 ppm each week. I'm still doing the weekly 100% water changes. Is it possible that I need to do smaller water changes so the right bacteria can balance everything out?

[gregzz4]

The bacteria live in the rock, not the water column, so you may keep on changing as you were

[makana]

Would an environment with high nitrates lead to an increase in bacteria that break down nitrates? Is it possible for my rock to be low in that bacteria?

I guess I will keep on and hope that one day the rock is usable.

[gregzz4]

You're not going to have denitrifying bacteria growing in your rock as they only 'live' in an anerobic environment ( like a deep sand bed )

All you can do is keep removing the nitrates through water changes

Did you buy this LR from another reefer, or was it a new shipment from a LFS ?

[makana]

I had a sick coral and was battling high nitrates in my tank. So I pulled this rock out along with enough water to start a small tank to house just the coral to see if that was the source. It was the source. I was doing massive water changes to keep nitrates down. Now my tank has zero nitrates, the coral is gone, and I'm trying to save the rock.

[ckmullin]

If the rock is loaded with garbage, phosphate etc throw it in an acid bath. It will clean the rock spic-n-span however you won't have live rock when your done. In some cases I can see doing an acid bath to have it 100% clean and then seed the rock fresh. You know then what your getting from the rock.