[mojoreef]

OK...so let me see if I have this right....there is no way of preventing the phosphates from getting into the sand bed, because it is already present in the sand, and essentially it will leach....because if it's in the sand then it is going to be in the lower zone.

You cant control the phosphates that are in the sand, unless you dont put it in. You can control an ammount of the phosphates entering the bed by not allowing the phosphates that are associated with detritus/food/waste and so on to enter it but kinda defeats the purpose. The concept now being purposed by the PHd's is to allow the cyano/algae portion of the phosphate cycle to occur and then to syphon the cyano and so on out, this way you are breaking the cycle and actually exporting something.

However, I can control the top portion by syphoning the upper layers, say during water changes

you could but you have to becareful. two things to look out for. One is watch for the sulfide zone (grey sand) hit that and you could have problems. The second is you have to look at the whole bed. You are going to have the ananerobic zone raiseing in the bed (along with all the products that a DSB doesnt process), now at the same time you are shaving off the top....at some point in time your going to meet, hehehe

and having good water movement trying to keep the detritus in the water column

yep thats what folks do that dont have DSB's, this way it keeps the detritus as a food source for those that feed on it, or it lands in the bed and feeds it instead.

What about trying to keep the critters in the sand bed fed in order for their job to be done. If I keep removing their food source, then I potentially won't have critters.

The larger critters in a dsb (pods/worms and such) are thier for what is called bioturbation. Thier movement allows for the migration of elements through the bed. They are not really thier for thier reduction capabilities. They will find food dont worry, lol

What changes can I do to the system to make it work

Boy thats a question that even the big boys cant answer. Hun the DSB is what it is. A DSB is set up to be a recycling center not an export devicd (with the possible exception of nitrogen) .

Macro algaes in the fuge to absorb the phosphates

You can do that for sure, it will allow for the absorbtion of nutrients (both P and N) that are in the water cloumn and happen to come with in grasp of them. As per this helping a DSB, no chance. the phosphates bound with in the dsb system that are leached will be taken up on the spot by algae and will not be available to the marco that is somewhere else. This is why cyano is so previlant with dsb's, Cyano is a super absorber when compared to macros.

Mike