I seem to be stuck between a rock and hard place with this aquarium.
On the one hand, the crypts seem to be recovering with a few new leaves appearing. On the other hand even some of the Java Fern is melting now and some of the new Marsilea growth as well.
If I increase the working pressure and open the needle valve fully, I can maybe get a drop of about 1 pH unit in a few hours. The problem is so much CO2 is wasted as the bubbles are quite big and leave the diffuser with such force that they break the surface.
A lot of bubbles go in the filter which is what I wanted. However, the filter soon starts to become really noisy and burp. CO2 bubbles also collect under the spray bar... However, if I reduce the working pressure/bubble count, the pH won't reduce enough.
I'm gonna try another pH profile tomorrow and I've ordered a bazooka diffuser which might help things.
The only positive is that I've got no algae yet.... despite the sick plants and ammonia there must be in there.
P