Hi Steven,
I really do appreciate you taking the time to respond. I like to learn, and having someone to give me info or suggestions is great!
So to answer your question about phosphates, as my tank is new-ish and the fish aren't really thriving yet the feeding is a bit difficult. I usually get into the habit of turning off my filter and then feeding some food. As the fish are sometimes hiding I believe a lot of the food falls to the bottom, and with no catfish, I kind of envision too much food build up. Things have been better lately as when I turn off the filter and approach the tank it seems that the fish are starting to learn that it is feeding time and will at least come out and eat. The neons tend to feed in the middle of the water column so they tend to ignore the food on the surface and what falls down to the bottom. Anyway, like you said, I did the phosphate test and even with my wife to look at the color chart with me, I was guessing my values were in the 0.25 - 0.5 range. So when I finally got around to doing my first fluval canister filter cleaning, I ordered a bunch of filters that they had like carbon, ammonia, and phosphate. I was just naive enough to believe that phosphates are not great in the aquarium and wanted to remove them. With there being excess food laying around, I thought getting phosphates out would be a good thing. I tried feeding frozen daphnia, and they weren't very interested, but seem more excited about crushed up flake food. As there are only 5 of them now, I usually just crumble up half a flake or so, so that there isn't too much wasted.
So since I changed the filter, my PH fluctuations have changed, not in amplitude, but around a different average. So for the week before I cleaned the filter, the ph would go from 5.8 to 6.1 and back again during the light cycle and dark cycle. After the filter change my PH now goes from 6.7 - 7.0 during the day and 7.0 - 6.7 during the non-lighted period. So I still get a 0.25 - 0.3 change daily but now it is at a slightly higher PH. KH is still between 0-1 and GH is still around 4-5.
Interesting that you mentioned the Phosphate tester as I had ordered that very same one a few hours before you posted that. The remaining 5 neons are still alive. They seem to eat when food is around. They do seem to hide low in the tank in the tall plants at times, which I don't think is a sign of things being good condition for them, but it is hard to tell. The otto's just seem to do their thing and never seem bothered by anything and the 3-4 amano shrimp I have just go about their business. I run my lights from 2-10pm EST, and run an airstone from 10-2 (when the lights are off)
After cutting off the CO2 injection, I've started to get a lot of hair algae. The otto's don't seem to be messing with it much, so I was thinking about what I should start changing and observing to try to get it under control. I have a Kessil 160 tuna sun that I put on for 8 hours total a day with a 1 hour increase to 80% intensity to start and 1 hour decrease at the end of the cycle to dark. I was thinking about maybe lowering the peak intensity. Currently I am only dosing with flourish at the recommended level once a week at best. So I'm not sure if the abundance of nutrients is the problem. The plants are starting to change to smaller leaf size with less growth as I would expect from the changes in CO2. I'm considering passive CO2 now, but I wanted to think about it a little more for now. I'm kind of wondering how much improvement I would see in plant growth with passive CO2 versus doing nothing.
Thanks again for your thought/information.
Drew