Ok,
I think that I am finally on to something, so I am going to go ahead and begin to document.
I have been testing PO4 since the beginning of the upgraded system. Each day, at 6am, I test, and gain insight from the previous day. What has stumped me, is seeing these wide ranges of swings, which I chalk up to unsteady biome, new tank stuff. Then I added the prop tank, again, new surfaces for dinos and cyano to take root, or at least until bacteria has seeded.
Now, I am an on and off user of bacteria, and recently I decided to test Re-biotic, and it's impacts on the mainly the display, some of the rock is older, has always been laden with funk, and frankly, never really restored to that clean rock look. Layers of algae, locked under funk, and laden with all sorts of stuff. That said, there are periods, where this gets better, but never to the full glory. My corals never skip a beat, but with my ocd, it bothers me. So, I began dosing, first impressions were that it reminded me of a zeovit mulm release, snow, everywhere, in July, in FL

Anyway, this took me to thinking of mulm, as per recent discussion between Sonny and Reefbum. After thought, and the premise of Zeovit, I then begin to connect the dots. The mulm, likely rich in P04, is snowing on the reef, everytime the zeolites are pulsed. This release, cleans the stones, giving them refreshed surface for bacteria additions to colonize, out with the old, in with the new. This mulm, is feeding the corals, as the snow breaks up in powerheads, and breaks down, the particulate size is able to be captured by the polyps as food. Here is the feeding mechanism of Zeovit, then whatever not taken as food, simply skimmed off, or food down the line for the biome. Again, rich in PO4, this is how our test kits send us on goose chases, instead of simple observations. See, it's not your test kit, levels maintained, its the bacteria, and providing enough of a field, for it to have to home, feed, die, and become food itself. This is why Zeovit is SO misunderstood, I am quite guilty of using this and other systems, without taking the time to know what I have now learned throught testing and observation. Now, I am not a fan of zeolites, why? It takes trace from the water, supposedly, hence the secret ingredients, and likely fancy trace supplements. That said, the core system itself is brilliant! As we plow ahead, I feel that there are other ways than a 2x per day pulsing of zeolites to feed mulm to our systems. So, I have disable the socks, and now allow anything to pass through the main system, prop tank, and sump, freely.
Re-biotic is doing a treat on the reef, and eventually, I will get around to a better analogy, but for now, it is doing EXACTLY what it claims, to a tee... I also use AF Bio S(nitrifying bacteria with DIY Coral Snow) I have been doing Re-biotic 2x per week, Weds and Saturday, and on Weds, the Coral Snow with AF Bio S. Now, keep in mind I test PO4 daily. My system, at it's core, less than bacteria dosing, or PO4 dosing/roids, is at a deficit. That said, I have a normal fish feed, normal filtration, and stay flat on N03, but need to dose PO4 via Phosphorous or Roids in order to maintain yesterday's number. So, 0.06-.08 has been my daily average, but sometimes, I get a whack number, and either dose, or discontinue daily dose based on the test. See, that will determine if I dose roids or phosphorous, or not. What I did not keep in mind is the effect of bacteria. Again, I only use Re-biotic 2x per week, and AF Bio S at 5 drops, with Coral Snow once. So, I did not take into effect bacteria dosing. Now, I am still unsure of which one is doing this, but here is something that I found interesting. Sunday, Monday, and Tuesday, nothing out of the ordinary. I see .06-.08ppm for PO4. Tuesday night, I added 10lbs of marco rock, which was soaked for 3 days in RODI to the sump. I actually spoke with Allan on this one. My PO4 on Weds morning was .14ppm, so that's weird... Likely, leaching from marco, no worries, I just test, and maybe allow that to be my P04 source for a spell. Well, yesterday was Weds, and I did Re-biotic and Coral Snow DIY, this morning .03ppm. Yes, .11ppm consumption in 1 day. Needless to say, today I fed 1/4tsp of roids, again, maintenance dose, but will need to supply 1ml of phosphorous to raise. So, I will be interested to see tomorrow, more to come on that.
Now, I have noticed that since the P04 gap narrowed, alk slowed, so maybe that means stunted growth, not sure, but I have been dialing back kalkwasser. So, I will look to what appears to be the large Weds bacteria additions, and the way they consumed .11ppm, anecdotally, of P04, and see if now my growth kicks back in, which would show more food availability, thus increasing growth and mineral consumption. Only caveat is decreasing the prop tank whites from 20% to 10% until this system matures a bit, then slow ramping.
Again, more to come, thanks for reading
Edit: P04 is tested in the water column, correct, otherwise, we would need to swab surfaces, where bacteria likely has far more than our test. My direction is understanding bacteria, and availability in the water column, which in turn is harboring p04, as a downstream food source. Again, not sure what PO4 in the water column, tested, actually represents, I think JDA has tried, on numerous occasions to convey this point. As a fyi...