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After adding another spoonful of dolomite and waiting two days, the pH
reads 6.4. Nitrate is at 70 ppm (no fish), KH is below 0.5 ppm, and
iron reads 0.0 ppm. It really soaks up those cations. It may be that the
fired Profile has H+ attached to the sites, and when emersed, the H+ is
exchanged for any Ca, K, or Mg ions in the water. One shouldn't have
this problem if the profile is mixed with clay as it is designed to be.
I added Osmocote pellets under substrate and potassium sulfate and
magnesium sulfate to the water. As the fertilizer dissolves, the cations
may be attracted to the Profile exchanging H+ ions to form nitric,
phosphoric, and sulfuric acids in the water column. These will not be
blown off by aeration. There must be a chemist out there who can
I'm just surprised that enthusiastic users of this substrate had not
noticed this before. Perhaps they have harder water.
Wayne Jones said...
> I take back what I said about Profile not changing the pH in my tank.
> Everything was fine for about ten days with just a filter running.
> Yesterday I finally got around to adding CO2 and planting the plants. At
> first I thought I was getting too much CO2 but then the next day I
> checked the pH and it had dropped from 7.4 to below 6.0 after the
> addition of CO2 and plants. I took a sample of water and aereated it and
> the pH would not come back up. So the pH drop is unrelated to carbonic
> acid concentrations in the water. I wonder what sort of acid the Profile
> could be producing? It is not the peat because the KH has dropped from
> four to zero. It looks like a strong acid is at work here. I think
> disturbing the Profile during planting released enough acid into the
> water column to consume all the carbonate in the tank.