No, I think whatever is preventing you getting to the conclusion of the test is possibly an underlying cause.
Something is going on, the fact that you are getting farther in is an indication that it may be working.
Without going into too much detail, what you are accomplishing is first the oxidation of organic material this is also reducing the biological oxygen demand that is PP’s first job.
- As strange as it sounds, you could have dumped a great deal of PP in the tank and (with good aeration) not harmed any of the critters.
- This is actually, what gets many hobbyists in trouble,
- it appears they can shortcut the process use a great deal more PP the next time.
What is critical with the parasites is that the tank gets to a point where there is a PP excess of at least 1.75-ppm. This is the point where the destruction of external parasites and if there are intermediate host, there possible destruction (depending on what and if they are).
- The colorimetric "feature" combined with your knowledge of the amount of PP applied allows you to know with certainty the conditions were met.
A couple of factors affect the efficiency of PP, higher alkalinity/ pH favor oxidation, lower pH favor the second stage, disinfection.
- That your pH is under 7, for that matter under 8 lowers the oxidation efficiency.
- Had I realized the extent of excess DOC, I would have recommended ceasing CO2 injection and
- would have recommended a little baking soda.
Hang in there, you are gaining what we call “experience.”
You are also setting conditions, which are favorable to the best opportunity success of the Fenbendazole treatment.
You are correct, you are going to prepare jello shots...
The fish can easily go 4-days without food.