Need sanity check on Deep Sand Bed Cleaning

[highergroove]

I have a deep aragonite sand bed ~4-6" deep, established for 10 years and I have let my tank maintenance go for awhile. I called in a company to help get it back under control and they plan to gravel vac a portion of the aragonite sand bed each month until we get nitrates (very high > 100) and algae back under control. I have always heard don't disturb that bottom layer but he thinks portions will be fine. I also am not entirely sure everyone knows about deep sand bed methods so I have reservations. Please sahre you experience, advice. They come on Saturday and I don't want to make a huge mistake!

 

[griss]

It's been a very long time since I've had a deep sand bed (early/mid 1990s) and that was a Jaubert/Plenum method. But, I've always heard you can vacuum a DSB if you do less than 25% at a time.

 

[Timfish]

Like Griss said if it's not too much at one time it won't hurt. Be patient and expect different types of nuisance algae, you're disrupting the current equilibrium and it likely won't be an straight forward shift to an equilibrium that favors corals. Don't let them strip out the phosphates, I'd keep PO4 above .1 mg/l for right now. I realized back in the '90s there's not a corelation between po4 and nuisance algae. What I started doing a long time ago to deal with nuisance algae was simply larger water changes and using straws or short pieces of small diameter plastic or pvc pipe or tubing to remove algae from rocks and urchins are great for keeping it under control. Now steel straws are available and work great and paper towels will remove al;gae off glass where magnets just knock it off and it will resettle pretty quick. (it was gratifying to see Hawai'i using the same basic technique for remediating reefs.)

 

[wvned]

The trick is the vacuuming part. You dont want the stuff in the sand to into the tank. It needs to go out the vacuum.
How big is this tank?

The last time I did this myself like a tank transfer. Took the rock out. Ditched the old sand. Put new in (1/4 as much) and put rocks back with 75% NSW and 25% water from the tank I took out first before anything was stirred. Nitrates from 100 to 25 and stayed there and then dropped slowly.