Prime interferences with test kits
Interesting comment about the prime, I've been doing 70% water changes every 2 /3 days. So chances are that I may not be able to detect the ammonia with my test. I'll read up on the seachem website when I get chance.
The fish are happy after aerating the water over night.
There are four suggestions of what could be wrong, please shout if I've missed anything, problem is that none of them are a good fit.
Ammonia from substrate
Would this still be being released after a month?
Adding a double dose of prime didn't help. The water changes fixes the problem that fits.
Would the bubbler manage to lower levels in a few hours?
Chlorine / chlorlamine in water
I also always add prime, which suggests the problem isn't with the water being added.
After a water change the fish were happy for 48 hours
I would also expect that when I added extra prime it didn't fix the issue.
High Co2 levels
I dropped my co2 levels right down till the drop checker is a dark green / blue and still the fish were gasping at the top.
I also repositioned the drop checker incase it was in a dead spot.
Low o2 levels
All the plants have been moved so growth and photosynthesis will be slower, I've also added a few more fish.
The timing doesn't really fit though, I would have expected all the fish to be struggling first thing in the morning, not mid day.
H zosterfolia is a fast grower, but not quite so easy to grow with the form shown in Tropica’s photo
I wish my H zosterifolia looked like the photo, the leaves are far more spaced out and less compact.
I was going to wait till it hit the surface before chopping it in two and replanting the tops.
Is there any way to make it more dense without reducing light?