My tank is 480 days old. I've been running Phosguard for the last 300 days to keep my phosphates in check. I measure with the Hanna Phosphate ULR. It's 0.02 - 0.04ppm for 3 or 4 weeks of running Phosguard, then goes up to 0.10-0.12ppm which is a sign to replace the Phosguard (75 gr for 80 gallon tank), next day it's back at 0.02ppm, all good.
Approx. 4 weeks ago it completely changed. I measured 0.00pm for the first time. I added Reefroids - this brings the phosphates up and removed the Phosguard. After 3 days it's back to 0 ppm, so I keep feeding Reefroids every 3 days, to avoid zero phosphates.
My nitrates are stable at 6-8ppm (Hanna Nitrate HR) dosing RedSea Nopox.
I don't do anything different otherwise in the tank, other than dosing some API Marine AlgaeFix to fight dictyota - but this is only since the last week. The phosphates bottoming out started happening a few weeks before that.
What could be the cause - have my live rock or substrate stopped leaching phosphates, have my corals suddenly decided to start consuming phosphates,...?
I'm not unhappy with this, as two ICP tests showed a high amount of aluminium in the water, but I'd like to understand the reason.
Approx. 4 weeks ago it completely changed. I measured 0.00pm for the first time. I added Reefroids - this brings the phosphates up and removed the Phosguard. After 3 days it's back to 0 ppm, so I keep feeding Reefroids every 3 days, to avoid zero phosphates.
My nitrates are stable at 6-8ppm (Hanna Nitrate HR) dosing RedSea Nopox.
I don't do anything different otherwise in the tank, other than dosing some API Marine AlgaeFix to fight dictyota - but this is only since the last week. The phosphates bottoming out started happening a few weeks before that.
What could be the cause - have my live rock or substrate stopped leaching phosphates, have my corals suddenly decided to start consuming phosphates,...?
I'm not unhappy with this, as two ICP tests showed a high amount of aluminium in the water, but I'd like to understand the reason.