I had never thought about the cleft in the algae ball before. I think maybe it's always been like that. Maybe it is dividing into two algae balls and it's just taking it's sweet time about it. It's the only algae ball I have ever had...I just assumed they were all like that.
For nutrients, every six days or so I add about 5 litres of water to top up the tank. There is no fertilizer in that, but I read somewhere that straight tap water is pretty good for adding nutriets, provided you add it often enough. (I just considered the math on that: that means I am losing almost a litre a day to evaporation. That can't be right. Can it? Hmm.
Then every three weeks or so I do a one-half water change. At that time I add:
~5ml Kent Botanica Fe Iron supplement
~15ml Plant Gro NPK 0.6-0.3-2.4
~10ml Seachem Flourish Nitrogen supplement
~5ml Kent Botanica Grow multinutrient solution
That's it for fertilizer. No root tabs or anything.
As for critters, I have:
7 or 8 assorted algae-eating shrimp. Maybe less. They are hard to find.
2 Siamese Algae eaters
1 Yellow Algae eater
1 mystery algae eater
3 er...tertras. Threadfin yellow rainbow somethingorother-I-forget tetras. They are nice though.
and far too many unwanted snails.