old sand bed?

[Pooky Barr]

My 90 gallon tank has been up and running for about four years with a sand/coral bed and live rock. Lately the rock seems to have a lot of "dirt" on it and the sandbed looks old-more like ash or dirt. Can anyone tell me what may be going on? Thanks

[Toddrtrex]

[welcome]

How deep is your sandbed? And do you have any clean up crew for it?

[mg426]

Might it be a layer of detritus???

[crvz]

<a href=showthread.php?s=&postid=13919148#post13919148 target=_blank>Originally posted</a> by mg426
Might it be a layer of detritus???

I imagine that's what's going on, a layer of fish waste and leftover food. Many folks will recommend getting clean up critters (snails, crabs, etc) to deal with it, but I always prefer the business end of a siphon hose to remove stuff like that.

[Pooky Barr]

The sand bed is about one to one and a half inches deep. I have several hermit crabs and about 20 snails of different varieties. I also suspect there are bristle wormsin there. I've used a water siphon and tried to clean the sandbed while doing water changes but the sand and rock continue to look dingy. Does sand and rock ever have to be replaced? Thanks for all your thoughts!

[Toddrtrex]

I don't think you have to replace it, but may have to do some work.

With that shallow of a sandbed, you could "gravel vac" it with each water change. But, since it seems like it is pretty dirty, I would start with only a section at a time.

I only have a sandbed ( shallow ) for looks and my anemones, so I vac all the open parts with each weekly water change.

[WaterKeeper]

Sand tends to decline in size over time though dissolution, with aragonite, and abrasion with silica sands. The finest is usually near the top of the bed. That is probably being stirred up and creating a fine silt in the water column. Since it is a shallow bed I'd vac off about a quarter inch of the bed and replace it.

[Pooky Barr]

Thanks for the info. To avoid stressing fish and disrupting corals and mushrooms-what is the best way to add more sand. Do you suggest live sand?

[WaterKeeper]

I sure do. Fresh LS provides all the organisms that denote a healthy bed. I'n your case I would only remove about 1/4 to 1/2 using a aquarium vac and place the new LS on top of the base. If you decide to go with a DSB add no more than an inch or so at a time so you don't crush the critters deeper in the bed.

[CnLHolman01]

I have had the same sand in my tank for 6 years and have a lot of critters in my sand. I wouldn't remove as doing this will disrupt your biological filtration.
Detitrus is normal. Is it accumulated around lr? May indicate that you have peanut worms in your lr (a good thing). I don't mess with the deitrus in my tank, other than to blow it off with a turkey baster (but if you vaccum it out during a water change it wouldn't hurt anything either). My mushrooms tend to really expand for a couple of days after the turkey baster to the detitrium.
Are your parameters out of whack? I would go by that.