Originally Posted by safina
What types of fish deaths? What were the symptoms?
Have you tested your ammonia, nitrIte, and nitrate levels recently between water changes?
Issues with proper dosing of Prime would be obvious immediately while doing water change itself and shortly thereafter. Fish gasping for breath at water surface, clamped fins, and in extreme cases- a quick death.
I have never seen signs of chlorine/chloramine poisoning after a water change so I don't think dosing Prime was the real issue. That being said, I have increased the amount of Prime I dose during water changes. I do still believe that dosing Prime for the entire volume of the aquarium is a little excessive if the goal is only
to de-chlorinate the replacement water. Now I am dosing for the amount of replacement water times two. For instance, if doing a 15% water change of 75 gallons (0.15 x 75 gallons = 11.25 gallons) then I will dose Prime for 22.5 gallons (22.5 gallons = 11.25 gallons x 2). That gives me plenty of wiggle room if I estimated incorrectly the amount of water changed in the aquarium. So far so good!
I religiously kept an "aquarium log" at the time I was having the most issues 2 years ago. I just reviewed it and knowing what I do now, I think I see the pattern that may have caused the issues.
I was keeping a 5-gallon and a 3-gallon aquarium. I was testing water parameters every 3-7 days and doing all of the regular maintenance you would on a larger aquarium. In order to keep the substrate looking clean, my weekly water changes ended up being large (50-80%). I was also just learning about EI dosing and the finer details of fertilizing plants. Between large water changes and dosing fertilizers, the GH would fluctuate between 7-12 German degrees and the KH between 3-4 degrees. I had read somewhere that top off water should only be RO water to prevent mineral buildup over time--so I started messing around with RO water. Lessons learned:
--Most people know KH can only be raised slowly (about 0.2 every 24 hours). Now I know GH also
has to be raised slowly (about 0.5 every 24 hours).
--Don't mess with RO water unless you really know what you're doing. Water treatment is way more complicated than I thought it would be.
--Try not to do more than a 20% water change per 24 hours. More than that may stress inhabitants (i.e., invertebrates such as shrimp are especially sensitive to sudden changes in total dissolved solids).
The types of disease I saw varied and I think it all came down to disease-susceptibility caused by a stressful environment that I inadvertently created.