Does my RODI take out phosphates?

If I recall correctly RO should remove most phosphates alone. DI definitely does. Do you have a high TDS out of the filter?

 

all ros take out phos

 

i had phos in my tank from fedding over

 

so what no use for a phosphjate reactor then? is over feeding the only way to end up with high phospates?

 

Ro's take out phosphates based on the membrane's rejection rate. The Di part will take out the rest in most cases.
Most fish and coral foods are packed with phosphates as a preservative. Fish, pods and most everything else living make organic phosphates with their poop. Depending on your rock and sand it can actually act like a sink for phosphates and retain them. Water tests really will not do much to detect this because cyano and algaes will consume phosphates so fast they'll skew the results of the test showing lower readings than what is actually there. This is also a problem sometimes for phosphate reactors.  Phosphate reactors will remove what is in the water coloum but do nothing for the source with. Extended use of a reactor should eventually win out. Activated carbon used to long can be another source for phosphates. The carbon captures organic material and if left to long the organic material will rot creating phosphates.
There have been some good threads on RC and some new methods out there that use bacteria to digest phosphates. When the bacteria consume the phosphates they eventually end up in the water coloumb. This allows your skimmer to remove them better.  Eventually it lowers the total nutrients in your tank.
I have been fighting phosphates for the last 6 mos due to a bad ro membrane. I've ended up researching some of the newer methods in reef keeping and can finale say I am making progress from increasing the bacteria in my tank.
Hope this helps

 

I just found this article on the whole phosphate cycle. I know like my previous post it does not really apply to RO/DI but thought it would give some a better understanding of how phosphates work and how they build up in the aquariums. www.skepticalaquarist.com/docs/nutrient/phosyc.shtml