what exactly do you mean when you say it started to release things? like the stuff in the substrate started to float out of it?
No, just active soils have a high CEC. They absorb stuff from the water. In my case apparently nitrates and phosphates. In a planted tank, they would probably be used up by the root system, so win-win. In my tank though, it wasn't plant, all shrimp, so at some point the soil gets full and starts to release. I'm not sure about the phosphates but the nitrates are for sure. I took 4 plastic container and put in plain RO water with minerals in 1, then 1 soil directly from the tank, one soil that I tried rinsing off for about 15 mins as suggested by 1 person. The last cup I had soil, that I had baked in the over at 200F for 20mins at the suggestion of someone else, a method they heard of from someone but never tried. I let them all sit for 24 hrs, shaking the containers a bit to get the water moving through the substrate.
Baseline Source Water - 0ppm
Soil Directly from the tank - 50ppm
Rinsed off soil - 2.5ppm
Baked soil - 20-50ppm and the TDS was 50 above the others in the container.
So through testing, my soil is loaded with nitrates and rinsing it off or baking and drying it shows it wasn't the water from the soil, it wasn't debris on top of the soil, it was the soil itself.
(baking the soil also stinks something fierce. lol)
I transferred all my shrimp over tonight, 60 in total (including 3 berried) plus the few that were already in there. Acclimated each since they came from a 5pH water to 6.7pH, where the tank is at now after adding a few doses of the Ebiken Sosei. TDS is 140 with Bee gH+, gH is 5 and happily nitrates are 0. lol.