Couple quick questions about binding/bound, leaching Phosphates.

[bklynreef]

To think for years i was wasting tons of money on gfo when LC would have done the trick. Truth is, everyone scared me about using it with my fish and thats wht i shyed away from it. Now after starting slow and careful with it im using it on a weekly basis directly in to my skimmer no 5 micron filter sock but do have 100 micron socks on the system. Keeping my PO4 between .19 and .06. Sps and corals showing more growth, feeding heavy for corals once a week, fish fed every other day just what i see they eat so it doesnt hit the sandbed. Nori every other day. My ATS is softball size every week and cheato growing in the fuge nicely. LC is my holy grail, now i can feed like i should have years ago without worry.

 

[sgrosenb]

Reviving an old thread here - I have always wondered why it is that when you strip out PO4 too quickly, even when there's a lot of PO4 left in the system (i.e. going from 0.90 to 0.30) that it can stress SPS corals substantially. My simple thought would be "well there is still 0.30 PO4, which is plenty, so it should be fine and shouldn't matter how quickly you go from 0.90 to 0.30". Clearly that's not the case.

On that same thought, I've also wondered about the best cadence to pull PO4 out of the water. I've run into the issue where, if I run water through my GFO reactor continuously, I either have to use a small amount which gets depleted quickly and creates a yo-yo effect, or I use a large amount and it strips out too much PO4 too quickly.

I finally settled on a setup where I use a lot of GFO, but only run water through the reactor chamber 4 times per day for ~30 minutes, rather than continuously running it. That works to keep my PO4 reasonably in check (I adjust the 30 minutes to something higher or lower as needed), but it clearly still stresses my corals.

I'm wondering if I'm creating a small yo-yo effect with that setup still, albeit shorter yo-yo's :) If, as @Randy Holmes-Farley states, PO4 releases quickly back out of the rock surface into the water to equilibrium, I would guess that my PO4 going on and off would cause an unwanted volatility in my PO4 even at small levels.

Anyone have thoughts on my approach, or how it could be improved?

 

[Randy Holmes-Farley Verified Community Expert]

Reviving an old thread here - I have always wondered why it is that when you strip out PO4 too quickly, even when there's a lot of PO4 left in the system (i.e. going from 0.90 to 0.30) that it can stress SPS corals substantially. My simple thought would be "well there is still 0.30 PO4, which is plenty, so it should be fine and shouldn't matter how quickly you go from 0.90 to 0.30". Clearly that's not the case.

The reason, IMO, is that corals can have many different ways to take up phosphate using different protein transporters. However, changing the number of these or types of these takes time, and in the meanwhile, a coral may not get enough P or may take up too much before it can adjust.

Lowering phosphate slowly is generally the goal, and that can be accomplished lots of ways.

1. Less GFO changed more often.
2. More GFO with lower flow through it. (or timed, as you do)
3. More GFO partially changed each time (not a 100% swap).