How often do I need to change my filter socks? My phosphates seem to be running high, and I'm thinking that I may be leaving them in too long.
When I used them I changed them every 3 days. Now I use filter cups with Polyfil in them. Just remove and throw away. I don't think filter socks will have much if any effect on PO4. How high is it?
HANNA read 43ppb or 0.132 ppm, but I was only changing every two weeks, so now I will change every 3 to 4 days.
That's not too bad actually. If everything is happy and you don't have any nuisance algae problems I wouldn't worry about it too much. If you do try to reduce it with GFO be careful and monitor it closely. Bottoming out PO4 can be a ticket to a dinoflagellate bloom.
I like to keep mine about 0.06-0.08. Lot's of really nice tanks have PO4 much higher than that. Mine has looked good in the past at 0.12-0.15. Stability is probably more important that the absolute number. I was proud of the last week or so of PO4 readings.
Yeah your po4 is not too high at all. Natural reefs are between .04 and .13 depending on the location. I wouldnt mess with that at all currently. You should be fine changing your socks out every 3-5 days. But I wouldnt let it go longer as I have observed nutrient climb if they are left in over an extended period of time. BRS did an investigates video on this also and I believe they found 4 days to be the sweet spot. Check it out when have some time. It's a well done video.