Deep Sand Bed questions: Getting one fired up and one has some black in it

[basssnake]

1. I have one tank(85 gallon 4ft long) that has been setup for 5+ years with a dsb of about 4". It has always kept the nitrates at 0 for the entire time(only once did my nitrates climb to 15ppm or so and didn't stay there too long). I am seeing a couple of black areas in the sandbed(the dsb is in the main display) and one area is about 1 inch wide and goes from just below the top of the sandbed to almost the bottom as it slightly tapers near the bottom. The other spot is about a 3inch circle and doesn't go to the very bottom or to the very top of the sandbed. This is what i am seeing in the dsb through the front of the acrylic on the front of the tank. Is there any need to be alarmed? I think i have seen these before and I think they disappeared, but i can't remember for sure if this has happened. Please give me any thoughts, advice, etc. thanks.

2. I have a Very large system running in another room. It has this for a setup: 180 gallon main display(1 to 2 inch sugar sized sandbed, around 200-300lbs of live rock, lots of corals, several fish, hermits, snails, starfish, etc.) 100 gallon rubbermaid plastic stock tank for a sump(6 inch deep sand bed, about 200-300lbs live rock, a few hermits, several serpent stars/brittle stars, and a Aqua medic turbofloater 1000 multi for a skimmer), this then drains into a 45 gallon refugium/sump which has about 20-30lbs of rock rubble, 4 mangrove trees, cheato algae and a few types of calerupra growing and a seaclone 150 skimmer. This tank has been setup for almost 2 yrs. The main display tank's sandbed has life in it as i can see worms in the sandbed. I used sand from a tank i broke down to seed the sump and display tank. Issue: dsb has never kicked in and done anything to lower nitrates. They have always been extremely high(100ppm + range). I feel that with a 6 inch x 4ft x 2ft dsb that it should easily be capable of doing the job. What could be the issue? Do i need to seed this sandbed with some different sand of some sort? The only flow in this tank is from the skimmer and the overflow from the main tank(which looks like a whirlpool in the sump as i have a down turned pvc fitting on the end) which i figured would move some water in there.

I don't know what to do on this to get this dsb to work. Any ideas, suggestions, comments, etc. would be appreaciated.

thanks for any help on the above issues.

[pitmindi]

Hi, there is an expert on deep sand beds on the forum of marinedepot.com. His name is Ron Shimek and his topic is invertebrates. He is an expert and very helpful. If you post a question he will answer it quickly. I know he says hermit crabs and shrimp are detrimental to a dsb since they eat the inverts that a dsb relies on. Hope he can help you.

[basssnake]

Thanks for the help. anyone else have some input?

[outy]

your getting close to the limits of a DSB, the black is bad areas of overloaded anarobic bacteria.

i threw out my first sandbed at 5 years to and had that in it so i just chucked all that sand.

my current DSB is at 4 years old and no black this time around so i may wash out the sand and re use it inmy next project

[outy]

#2 the DSB is working its just not big enough to keep up with the bio load

[basssnake]

Anyone have some more input on these issues? thanks

[The Escaped Ape]

DSBs have to be maintained well. Part of what will make this work is having the right CUC, including conches and nassarius snails to keep the sand bed turned over.

[chimmike]

Originally Posted by The Escaped Ape

DSBs have to be maintained well. Part of what will make this work is having the right CUC, including conches and nassarius snails to keep the sand bed turned over.

I've read some things recently that say this is not true and does not help, as those guys can easily wipe out the entire bacterial colonies in the DSB thereby defeating the purpose of the dsb.

Rather they say the dsb should be simply left alone. No CUC in there to eat all the helpful creatures in the bed.

[outy]

Originally Posted by chimmike

I've read some things recently that say this is not true and does not help, as those guys can easily wipe out the entire bacterial colonies in the DSB thereby defeating the purpose of the dsb.

Rather they say the dsb should be simply left alone. No CUC in there to eat all the helpful creatures in the bed.

its only partialy true

anarobic bacteria stays down deeper then a CUC gets, allthough the thin layer of sand on top does play a big part in it, a DSB will still function properly with a CUC as the top layer comes back pretty quickly.

A DSB boes have to be maintained but not nessesarily by a clean up crew. In a closed system like we run a DSB generaly has a time limit before it becomes saturated with detritus and needs to be cleaned and or thrown out and started over. generaly speaking 5 years is about the life span allthough there are rare cases where they can last longer,, key word "generaly speaking"