Here is SeanT's rock cooking recipe -
2. Tubs to cook rock in. And an equal amount of tubs to hold the rock during waterchanges.
3. A few powerheads.
4. Plenty of buckets.
5. A smug feeling of superiority that you are taking it to "the next level."
6. Saltwater, enough made up to follow the instructions below and to replenish your tank after removing rocks.
Here are the steps:
1. Get into your head and accept the fact you will be making lots of salt water if you aren't lucky enough to have access to filtered NSW.
2. Explain to significant other what is going on so they don't flip out. This process can take up to 2 months. Prepare them in advance so he/she can mark it on the calendar and that they won't nag about it until that date arrives.
3. Setup a tub(s) where the rock is to be cooked. Garages are great for this.
4. Make up enough water to fill tub(s) about halfway and around 5-7 buckets about 60% full.
5. Remove all the rock you want to cook at this stage. (The rock can be removed piece by piece until you are done.) I suggest shutting off the circulation beforehand to minimize dust storms.
6. Take the first piece of rock and dunk it, swish it, very, very well in the first bucket. Then do it again in the 2nd bucket, then the third.
7. Place rock in the tub.
8. Repeat steps 6 & 7 to every piece of rock you want to cook at this time. The reason I suggested 5-7 buckets of water will be evident quickly...as the water quickly turns brown.
9. Place powerhead(s) in the tub and plug in. Position at least one powerhead so that it agitates the surface of the water pretty well. This is to keep the water oxygenated. You can use an air pump for additional oxygenation if you wish. Only one powerhead per tub is needed. Remember the powerheads main responsibility is the oxygenation of the water.
10. Cover the tub. Remember, we want TOTAL darkness.
11. Empty out buckets, restart circulation on main tank.
13. During the first couple of weeks it is recommended to do a swishing and dunking of the rocks twice a week.
What this entails is to make up enough water to fill up those buckets and the tub the rock is in.
First, lay out your empty tub(s) and fill buckets the same as before.
Then, uncover tub with the rock in it. Take a rock and swish it in the tub it's in to knock any easy to get off junk.
Then, swish it thru the 3 buckets again, and place in the empty tub..
Repeat for all your rocks.
Then empty the tub that all the rocks were cooking in, take it outside and rinse it out with a hose.
Place tub back where it was, fill with new saltwater, add rocks and powerheads, and cover.
Wait again until the next water change."
It sounds like you need to put your powerhead on the top.