Let me first acknowledge that I have some experience in freshwater community tanks but have not had one for the last 10 years. This board is awesome and has made me realize how much I don't really know. So here I am, and I need a little advice.
I have a 75 gallon, non-planted tank that has been set up since the 1st week of Feb. I have 2 medium and 2 large Malaysian driftwood pieces in the tank. Filtration is through an Emperor 400, which I've left alone other than to change the filter cartridges and add some additional carbon to the media baskets. I supplement water movement with a couple airstones at the moment. I have used Special Blend and Nite-Out products to help promote cycling.
pH was high early but since the driftwood was added has been pretty consistent at 7.8. I test hardness and alkalinity via strips, which have also been pretty consistent (120 hardness and 80 alkalinity). My tap water is very high pH (at the limit of 8.8 on my tesk kit), which I pull down to tank levels using Seachem's neutral regulator when I do water changes. I don't think this is a sustainable approach, am interested in thoughts about managing the pH since the tap is so high.
By the end of Feb, ammonia had peaked at about 1 but returned to zero...nitrities never did register, and nitrates were barely detectable. I got brave and added my first fish. I started with 6 cardinal tetras, 2 guppies, 1 pleco. That was about 3 weeks ago, and all tests continued to read stable. Then I got braver and about a week ago added 3 angels and 2 cory's. (I know these particular fish would be happier in larger quantities but wanted to be sure water was ok).
Since then, ammonia increased to .5, then backed down, today it is at zero. Great. But nitrites rose daily and when it reached about 4, I worried. Added some Prime to the tank to take it down, and it did as a reading later in the day was at zero, but a day later I'm back to 4 or maybe 5. Not great. So I dropped a little more Prime in the tank this morning. I don't like the yo-yo trend. Nitrates have run about 5 this past week, but looked even lower today. I've been changing about 10% of the water weekly but this week have done 5-10% daily with the spiking nitrites.
Overall my fish seem to be fine, they are active, eating, don't appear highly stressed. I am feeding flakes 2x a day, and sparingly.
Water has been a little cloudy from time to time, which has had me considering additional filtration. Am interested in an Eheim cannister but an overwhelmed at the options and haven't pulled the trigger. In the meantime I just need to get my water stabilized.
I am interested in your thoughts. Is 4-5 nitrite a crisis mode or am I more worried than I need to be? I suspect I added fish too quickly and didn't properly stimulate the cycling. What is the best course of action given where I'm at? I think I need to crank up the water changes, at least short term. I've also considered adding a few live floating plants, to see if that would help. Long term would love to consider a planted tank but don't have any experience there.
Thanks very much for your perspective. This forum is great.