Lets see if I can describe this...

[Fish]

Hi all,
I am planning on changing the substrate in my 2gal nano from crushed coral to fine sand.


http://www.canreef.com/photopost/data/500/1185050228_008-med.jpg


Concern:
The water in my tank sinks through the substrate to an undergravel filter and a bulkhead in the bottom of the tank. This bulkhead leads to an eheim cannister filter.

Question:
Right now, the water drains throught the crushed coral as fast as it is pumped back from the return line. If I go to a fine sand, will that slow the draining water down too much? If the water can't drain as fast, it will slow down my circulation rate and might even cause my filter impellor to cavitate... right?

I appreciate any opinions that you can give.
Thanks,
- Chad

[albert_dao]

Wouldn't a fine sand just get drained into your canister?

[G1GY]

Fine sand will not work for you unless your outlet from the tank is above it.

[cpenner]

I love that little tank though.....

Where did you get it?

[Fish]

Wouldn't a fine sand just get drained into your canister?

Albert,
I entered the hobby after the undergravel filter trend had already died but I'm sure it wasn't uncommon to have fine sand on top of an u-g filter was it? I believed the material they used was called "filter tidy" or something. I was just planning on cutting a fine media bag or filter sock and laying it between the sand and the u-g filter plate. I'm 'pretty confident' that it would keep the sand from getting into the cannister filter.

- Chad

[Fish]

Fine sand will not work for you unless your outlet from the tank is above it.

Gary,
Is it because the water wouldn't drain through the sand fast enough?
Thanks,
- Chad

[Fish]

I love that little tank though.....

Where did you get it?

Thanks man,
I had IA aka Bow Valley Aquarium here in Calgary build it for me to my specs.



Anyone else able to comment on whether or not the water would be slowed too much by a fine sand?

Thanks,
- Chad

[G1GY]

Anyone else able to comment on whether or not the water would be slowed too much by a fine sand?

Thanks,
- Chad

The water would be slowed going through the sand unless it was suspended like it is in a fluidized sand filter.

Also, how do you keep it from falling through the under gravel filter grate?

If you did find a fine enough grate, the water pulling down through the sand combined with detrites would turn your sand bed into concrete in no time.

[G1GY]

Gary,
Is it because the water wouldn't drain through the sand fast enough?
Thanks,
- Chad

Yes.

Fine sand will make a more positive seal because all of the granuels will just fit together sort of like lego.

I'm just wondering.

What's to stop the whole tank from draining down if you have a cracked, broken fitting or hose?

If it's a check valve, those things are not very reliable IMO.

Maybe a small standpipe hidden inside a rock pile for safety would be a good idea?

That way you could use fine sand and have a little peice of mind that you'd never loose all the water in the tank.

Just a suggestion though. :smile:

[Fish]

Gary,
Thanks for your input. I was kinda worried that it wouldn't work with the sand. I realize that if there is a cracked seal or something the whole tank would drain completely empty. The risk is lower though because the tank is pretty thick glass, the fittings are secure, and the entire thing is a closed loop which is a "more" safe way of moving water outside a tank. I would have liked a standpipe intake - more for the surface skimming benefits - but there is no way that I could have hidden it as well as under the sand bed. Also if it was a safety concern I would have to raise both the intake and outlets with standpipes because a failure anywhere in a closed loop would drain the tank level to the lowest bulkhead. I personally do not believe a failure is likely but if it ever did happen, it would be a pretty minor setback. I mean, 2gals worth of livestock isn't too bad :razz: .

- Chad

[Cap'n]

FWIW, I have an eheim cannister on my system which has accumulated a couple inches of fine sand in the bottom of the media area. Still silent, still works perfect.

[Snappy]

I have fine sand in my 27 nano and I find that the outside filters slow down a great deal if sand gets stirred up. I think your flow would eventually slow to just a drip over time. How will you clean the media bag/sock once it is plugged with silt? I think it might become a nightmare for you to maintain.

[Fish]

Thanks everyone for your input, and good point about maitenance. I suspect that you guys have saved me a lot of time and heartache. I am planning on getting three or four stomatella and two or three ceriths to work on keeping the cc substrate turned. Does any one know if ceriths will still dig through small crushed coral? Or do they only do that in sand?
Thanks again,

- Chad

[danny zubot]

I'd say get a conch but the tank might be too small to support it. Also, I've seen people use a layer of fine screen under sand beds to keep the sand from falling through the bed filter if that helps.

[Fish]

Ya, to bad there's no such thing as a mini-conch. I had thought of using a fine screen under the sandbed but now I'm worried it might get plugged over time and require the sand bed to be dug up to be cleaned. ?
Thanks for your thoughts.

- Chad