Hi jason,
I did a trial some weeks ago :
here are the results :
my issue is :
I put 1 ppm of PO4 in my tank, 5 minutes after I checked the PO4 in my tank and it was @ 1ppm (confirm with a standard made by myself) so the PO4 is in my tank at a good concentration : (liquid fert is ok and is not the issue)
12 hours after adding 1ppm of PO4 in my tank, I checked the PO4 in my tank and it was @ 0 ppm !!! so the question was where was my PO4 ???
what I did :
https://barrreport.com/threads/is-aquasoil-ada-amazonia-light-powder-pumping-po4.14444/
I put ADA aquasoil with RO water, immediately checked the PO4 and it was @ 0ppm
I put ADA aquasoil with a standard solution of PO4 1ppm, immediatelty checked the PO4 and it was @ ~0.5ppm (PO4 already pump by aquasoil)
I put a standard solution of PO4 1ppm as standard, immediatelty checked the PO4 and it was @ 1ppm
I waited 12hours (1 night) and checked the PO4 again
I put ADA aquasoil with RO water - 12 hours after : No PO4
I put ADA aquasoil with a standard solution of PO4 1ppm - 12 hours after : No PO4 !!!
I put a standard solution of PO4 1ppm as standard - 12 hours after : 1ppm of PO4
So the conclusion for me was : ADA aquasoil was pumping my PO4 and the PO4 was in the soil et available for roots plants
BUT
since some days I saw some bubles with some solid and precipitate on the top of my aquarium
I stopped EI dosing and here is what I did in my tank :
- day 1 : No liquid fert : no bubles
- day 2 : addition of KNO3 only (NO3 = 3.4ppm) : no bubles
- day 3 : addition of K2CO3 only (K = 3.4ppm) : no bubles
- day 4 : addition of K2SO4 only (K = 3.4ppm) : no bubles
- day 5 : addition of KH2PO4 (PO4 = 0.6 ppm) :
BUBLES !!! (after a few hours)
I took the bubles and checked the PO4 and bingo, it was the PO4
at the same time, if I took the water of my tank without bubles, my PO4 is 0 ppm !!!
conclusions :
tank water without bubles : PO4 = 0
tank water with bubles : PO4 > 8 ppm !!!
the questions are why PO4 is precipitated ?
1) PO4 reacts with ADA aquasoil and precipitates ?
2) PO4 precipitates because my KH is too low (I add only RO water and just a few ppm of K2CO3 as a buffer) ?
3) PO4 reacts with someting in my water column but what ?
I will do some trials and keep you inform but my PO4 in my column water of my tank is always @ 0ppm