Ok I know I did something to cause this but I don't know what or what to do about it. Here's what I did.

Three days ago I decided to do a major pruning of my tank. It was basically one solid mass of hygrophila with some other plants growing in the shade of it. Also I upgraded my lighting ODNO from 1.25 watts/gallon to probably around 2wpg. In the process, I had to remove all the plants from the tank and then sort them out and prune out some nice pieces to put back in. I threw out probably half the plant mass in the process.

CO2 has been at pretty stable but low levels, right now according to my 4KH drop checker it's probably around 15ppm, perhaps a bit higher than it has been in the past.

I also did a 50% water change which would have temporarily reduced co2 levels and diy is slow catching up. I also started dosing calcium chloride for the first time as well since my tap water has 0 GH, and my nitrates are higher than normal right now since I dosed a lot, I wasn't sure what the uptake would be with the higher lighting (~40ppm). At the same time of the water change I dosed potassium, phosphate, Plantex CSM+B and magnesium as I normally do.

Now I'm seeing leaves starting to die off. My instinct is that it's CO2 related, but at the same time I've had low co2 for a long time and haven't had these issues before. Also my ludwigia which was growing like mad up until the pruning has now lost most of it's leaves, another ludwigia plant all the leaves went transparent looking and I had to throw it out. At the same time, some of the hygro is pearling now and I've only had the lights on for an hour so far this morning. Also my Alternathera rosaefolia which I just added to the tank is showing some color loss, almost like color flaking off, on the undersides of some of the leaves.

What's up with this??? Could it be from having the plants out of the tank? Should I reduce or increase the photoperiod? Should I dose anything else? I'm working on CO2 as much as I can.

Update: The leaves on some of the plants continue to disintegrate, and today I saw that two of my anubias plants are having the same disintegration issue. Also I lost one dwarf gourami. I did a full battery of tests and couldn't find anything wrong, ammonia 0, nitrite 0, and nitrate had dropped from around 40 to below 5 in the past two days. Must be lots of uptake happening. pH is around 6.5 with the co2. I also cleaned out my co2 thing last night, it was a little clogged on one bottle slowing down the flow. This morning my drop checker still wasn't really in the green level though so I don't think co2 overdose is the issue with the gourami, although my co2 is now probably higher than it's ever been at this point. CO2 doesn't seem to have a lot of effect on anubias anyway....they've never shown any signs of anything before so this is mystifying. I did an immediate 50% water change today when I found the dead fish and redosed ei, lightly; and left off the calcium in case that was an issue with the fish dying (not sure what I'm dosing, just assuming it's calcium chloride)...but if it were I should be seeing issues in my other tanks too or with other fish. I don't know, I'm stumped.

Here are the anubias. Could it be too much light? The ones that are disintegrating are also the ones probably in the most direct light, and I just increased my lighting to 2wpg.

Hi,
In general greater light=>greater CO2 demand. If you increased light without also increasing CO2 levels this could create a carbon deficiency. Having low CO2 for a long time and being OK all goes out the window when the throttle is opened by increased lighting.

Cheers,

Hm. Ok that may be the problem. I guess it will just take some time for the plants to adjust, right? 2 wpg doesn't seem totally unreasonable for diy co2 operating around 10 - 20 ppm is it? I am increasing co2, it's just happening slowly. My 4KH drop checker is finally green, just within the past couple of hours though. The anubias are what's really throwing me, I've had co2 go up and down all over the place and never saw any difference with those plants, but maybe it's just the lighting increase that's pushing them over the edge. I may move them all into the shade and see if that helps.

Would decreasing the photoperiod help for a while?

This is definitely the issue, I think. It's only the anubias in direct light that are having this problem (which I moved into the shade today), and otherwise it's mainly the hygro. I assume that since hygro grows so fast, it has to quickly get carbon from somewhere so it cannibalizes it's own leaves to get it. Other plants aren't growing as fast as hygro so they are just stalling out until they adapt. I have my drop checker in the green now consistently so I'm hoping the problem will resolve itself soon. The new plants are sending out new growth all over the place, they seem just happy to have co2 now.