Id like to keep corydoras julii and they need a ph of 6 to 7.5 could i add peat moss to make a difference?
It will not make a difference here. That is why I asked about GH and KH previously. The pH is tied to the mineral in the water (GH) and the KH acts as a buffer to prevent fluctuations. So the higher the KH the more steady/stable the pH will be, because it will resist other factors.
This is why one needs to first reduce the GH/KH if you also want a lower pH.
There are other factors affecting pH, from CO2 and additives the water authority may use, etc. But with the GH of 12 dGH and KH of 6 dKH here, and the pH around 8 in the source water, it is not going to be affected much by organics such as peat.
You didn't mention pH adjusters, but I will just mention that the above also explains why chemicals to lower pH do not work and are dangerous; they lower the pH immediately, but over the next few hours the buffering capability of the GH/KH bring it back up.
Now, having said that, to the
Corydoras julii. If this is the true species, it will be wild caught and would fare better in softer water long term. I said true species because
C. julii is quite rare in the hobby, since it occurs in rivers and areas that are generally not heavily-fished commercially and is therefore seldom exported; the few times it does appear it has probably been collected in the Rio Para which is regularly fished. The "Julii" cory most often seen in stores is more likely to be
C. trilineatus. The true
C. julii has a spotted pattern on the head and body, and the lateral stripe is either not present or extends only midway along the body.
C. julii is also somewhat smaller and more compact-looking in size than
C. trilineatus.
