Need advice - Replacing crushed coral w/ sand

[jester50]

My next improvement to my tank is to add live sand to the system. I currently have crushed coral substrate. This is for a 40 gallon. Filtration is live rock, skimmer, and refugium w/ Chaetomorpha. Inhabitants are 2 clowns, a burgandy star, hermits, turbos, 2 dusters, 2 cleaner shrimp.

I was planning to collect the sand from the ocean. The problem is - do I add the sand over the existing substrate? Or do I have to dig out as much of the current gravel first?

Im also wonderingif I should expect a mini cycle by adding the sand? I'll have to place it in my curing tank.

 

[benjen]

How deep is your crushed coral and do you currently vacuum it regularly to get debris out? That will help determine if you can keep it as part of the sand bed. You probably don't want it to be more than 25% of the final sand.

If it is temperate sand, excpect some die-off at tropical temperatures, Also make sure that it is legal to collect.

 

[jester50]

re:

My current substrate is 2" deep.

I do vaccum it every water change. Usually every 3 weeks.

 

[benjen]

jester50,

Then you can probably take maybe half of it out and add enough play sand to go to 3.5" or more. If you don't mind doing closer to a 5" sand bed than a 4", you can probably leave it all in. The sand will fill in around the coral and you may want to stir it a bit as you add the first couple of inches, so that you don't have 'air pockets' only with water...

You might either want to do this in stages or take your fish out, just to avoid a big sand storm. Vacuum before you add the sand and add enough to at least cover the coral if you go in steps. I haven't replaced substrate with my fish in the tank yet. Maybe someone who has can comment.