I thought I would post this up because when I started out I couldn't find any reliable information on if this could be done or not. I'm relatively new to aquarium keeping so my terminology sucks. I'll try to be as clear as possible.
I have a planted 2.75 gallon glass bowl for 1 HM betta. 3 types of plants: water wisteria, anacharis and I don't know the name of the third; 2-3 plants of each kind, 8 plants total. Over a few months I have managed to created what appears to be a completed nitrogen cycle with relatively little stress to the fish.
The first couple of months I just had large rocks in the bowl with the plants. I would change about half the water every week and half. This was not working. Ammonia and nitrates were still reaching dangerous levels.
I have a 6 gal tank that I use API bio-chem stars in so I took 3 stars and put them in a filter medium bag and buried it under the big rocks in the bottom of the bowl (kinda as a last resort). These rocks are all about 2-3" across so by "burying" I mean I formed a of cave around the filter medium bag - of course being careful to not leave spaces for the fish to go inside. (This is difficult, I observed the beta carefully for a few days to make sure it was secure.)
I then jam all the ends of the plants into the crevices of the rocks to secure them down. Since these are all plants that can be floated, they don't need soil, or at least don't appear to as they are thriving (I've already had to trim all three types back because of rapid growth).
I did the next half water change at 1 and half weeks to lower the ammonia. Then 2 weeks later I changed out another half.
After that I did 1/3 water changes every 3 weeks.
Ammonia levels went to 0 after about 3 or 4 weeks. Hitting 1.5 ppm at highest.
Nitrite levels were very high after ammonia disappeared, about 2 ppm, possibly more. This was nerve racking and I was carefully monitoring the fish to make sure he was taking it okay. He was sluggish but showed no other signs of distress. Possibly due to the presence of Indian Almond Leaves, but then again, I'm just a fan of them.
I kept the pH at about 6.8 during this time with plenty of IALs, which my fish loves.
After about 4 weeks the nitrate levels dropped to 0 ppm.
I do 1/4 water changes once a month (suctioned from the bottom) and maintain:
temp at 76-78 deg
a pH of 6.8
0 ppm Ammonia
0 ppm Nitrites
10 ppm Nitrates
and I always float 1 small IAL just because my boy loves it.
Does anyone think I need to change the water more often than this for some reason? I can't think of why, as far as the levels, it just seems like a long time to go without new water but then again the fish appears social, active and relaxed.