sand switch question

[piranhaking]

I plan to switch from crushed coral to sugar sand in a tank im working on at my school. The tank has a CPR hob filter/skimmer. The filter has some type of blue ribbon like filter media in it. After removing the CC i plan to put alot of it into mesh bags or nylons or something similar to allow the bacteria to seed the new sand. Would it be ok to add the fish back to the tank a few hours after the switch once the sand storm settles down some, or would it cause to much of a cycle. I would assume that by having a bio filter on the tank and leaving much of the existing substrate in the tank (in bags) that it wouldnt cause much, if any of a cycle and the fish should be fine. Any links to articles about switching substrate would also be appreciated. thank you.

 

[AllenFord_SC]

Digging out the CC could release some toxins into the water and also cause an ammonia spike. I would completely remove the CC and test your water parameters for Ammonia, Nitrite, and Nitrate before adding the fish back in.

 

[brettandlyndi]

I did this type of switch, from a marine white sand to aragonite. I didn't leave any of the old sand in, but used all the same water and rock, and didn't have any cycle. If you plan on keeping the old sand in there to seed the new sand, I would think you should be fine and not have any cycle.

 

[piranhaking]

The tank currently has an ugf so anything that is in the substrate would be in the water anyway. any more input?

 

[piranhaking]

anyone else have anything to say about it?

 

[Blown 346]

If the tank doesnt have any liverock, then most of the bacteria is going tobe in the CC.
By taking it all out you will see a cycle. I would take out sections at a time. One week take out a quarter and replace the quarter you took out with sand. Do this every week until all of the CC is gone and you have sand as a substrate.
This will prevent a cycle from happening. Then you dont have to take the fish out.

 

[Wryknow]

Clever idea.

 

[piranhaking]

I got the switch done last thrusday. So far ammonia has been 0. I tested it thursday after the tank settled for an hour or two, monday, and today. I got a slight reading on the nitrIte but is was less than .1 which is as low as the test kit reads. Nitrates were up to over 60. Now they are down to around 45. Im still doing water changes to try to get them down as i am able to. There was quite a bit of junk that settled on top of the sand and syphoning it out made a cloudy mess of the tank again, but im hoping a couple more cleaning runs will have it taken care of. Unfortunatly the tank still needs another bag or two of sand so as soon as i get the junk out and the sand comes in (i had to order it) it will be cloudy as ever all over again.