Carissa, thanks!

I think your problem was the introduction along with removal of co2.

I agree. I don’t know what I was thinking.

Plants get used to having a certain amount of co2 …if co2 is in abundance, they don't need nearly as much of this enzyme and thus reduce their stores and use all their energy for growth instead of producing this enzyme. If co2 is suddenly reduced, you have a bunch of very crippled plants.

This makes sense. I have seen leaves with holes in several plants, and several species dying off altogether, while the alga grows at will. However, I’m certain the DIY CO2 I had running did not provide an abundant or stable amount of CO2. The levels may have been sufficient for a day or two each time I changed out the sugar/yeast mix, but I imagine it dwindled to almost nothing over a week’s time. Therefore I think it’s interesting that the plants would need 6 weeks to adapt to the loss of highly variable CO2 levels.

For a non-co2 tank, you need to stay with low light, and therefore you need to stay with low light plants.

I’m prepared to do that. I bought some healthy-looking crypts today (“My First Crypts”)—a red, a bronze and a green—in anticipation of more stem plant die-off.

In the meantime, you should keep things stable - get yourself a dosing schedule, fertilize 1x/week with EI as you normally would in a non-co2 tank, and I would go with about a 30% weekly water change.

My plan is to add Sea Chem Equilibrium at a dose of 1/2 teaspoon per 40 gal weekly, along with 1/8th tsp. KNO3 and a few drops of monosodium phosphate once a week or two, as per Tom Barr’s non-CO2 article. As for water changes, the same article specifically recommends no water changes (an extremely appealing idea, I must admit). As I understand, weekly water changes "fools" the plants into thinking “hey, the CO2’s back!” which helps encourage algae growth, because algae are faster to respond to CO2 fluctuations than plants. It seems that a better course of action might be to just bite the bullet and do no water changes until the plants adapt to no CO2 and no Excel over the next few weeks—except that feel compelled to do a water change if the fish appear significantly stressed or uncomfortable. The fish are much more important to me than the plants. This is why I did the large water change at the beginning of this week.

Personally, I would reduce the photoperiod to about 6 hours/day to limit the amount of algae outbreaks.

Currently it’s at 10. I suppose 6-8 hours might help dissuade some forms of algae, but I can’t imagine it would help lessen brush algae or diatoms that thrive in low light levels. In any event, I’ve been thinking about two-4 hour photoperiods with a 2-hour break in between.

Keep removing the algae as fast as you can.

I did another clean up today (without a water change). I gave the swords and java moss another “buzz cut”. I took out all of the dead java fern. I removed, bleached (19:1 solution) then dechlorinated the H. leucocephala and the anubias—I see no visible algae on them now. I removed the rocks for cleaning; they are being soaked in 19:1 water:bleach solution as we speak. I scraped most of the algae off the glass, and spot treated the largest red algae colonies on the driftwood with Excel. Alas, I expect it’ll be back with a vengeance next weekend.

Perhaps reducing the lighting intensity could help too....I'm not sure but someone else might know if this will have an adverse effect on the plants or not.

I was hoping 1.75 wpg was within the realm of low light. Perhaps I should get more floating plants…frogbit, perhaps. Not duckweed.

Get lots of algae eating fish.

I’d like to, but I’m fully stocked at 1” per gallon. In fact, I wonder if my relatively heavy fish load is part of the problem. The platies and gouramis frequently peck at the algae but they can’t keep up with the onslaught. I did get 2 bristlenose plecos but they are still in quarantine. I hope that with the proper balance of light, ferts and plants, I wouldn’t need lots of algae-eating fish.

Keep ammonia at 0 at all times, it triggers algae

Never have had an ammonia problem since the tank cycled, luckily.

Keep dosing Excel.

Really? Is that necessary?

Your tank is in transition phase now, you just need to keep it as healthy and stable as you can until it sorts itself out.

I'm trying but it's hard to remain patient. Thanks for your recommendations.