OK< what am I doing wrong with Phosban?

[boobookitty]

I have a decently high tank phosphate reading of around 1.2 on my 75g reef, and I've bought Phosban in an attempt to lower that. I have a Fluval 404 canister filter that feeds a CSL UV, and I removed everything from the canister and put half a Phosban 150 container each in 2 different filter bags (no washing, packed fairly tightly, per instructions), put them in one of the baskets (one per side of the basket) with floss on top and bottom (per instructions), and started up the canister. I measured the output of the canister in an attempt to get it to a phosphate reading of 0, per instructions, but I didn't even get close - I dropped the canister output to as low as 8 gallons per hour, and the phosphate reading on the output stayed at 0.8.

So I reopened the canister, took a second Phosban 150, repacked it so that each side of the basket now has a full Phosban 150 (each of which is supposed to be good for a 150g tank), made absolutely sure that water flow has to go through the Phosban, started up the Fluval, and once again got the output as low as around 10g/hour - and the damn phosphate stayed at 0.8, with a tank phosphate of 1.2.

The kit is good - I've tested with 2 different kits from 2 different manufacturers with the same results. I can't imagine dropping the flow rate any lower, since it would be worthless; it would take 15 hours to turn over the tank volume at 5g/h, for example.

Anyone with any Phosban experience know what I might be doing wrong?

bbk

[boobookitty]

^

I'm thinking that the water flow in the canister isn't being forced through the chambers. It's a Fluval 404 - is there a way to make sure it's flowing through the Phosban?

bbk