S. Repens losing all its leaves suddenly

So a couple days ago, all my s repens in my tank dropped like half their leaves. All my other plants look great, and the s repens has been growing and propagating awesomely in the tank for the past 7 or so months. I use Flourish Excel Seachem 3 times a week, everything is planted in Fluval aquasoil, I have Seachem Flourish Tabs in as well. No CO2. Tank is about 77 F, I do weekly 20% water changes. Pic attached from just before this started happening so you can see all the plants looking good. No new livestock recently.

Recent changes that may have effected something:
-We had a local cold snap, and the water in the tank dipped to around 74.5 F
- The tiger lotus has been in about a month
-I recently reduced my light hours from 12 to 9 to combat algae
-The root tabs are a recent addition, been in about two weeks

You can't really see in the picture since it doesn't show the whole tank, but I have a ton of s repens along the front in various states of maturity. All of them are dropping leaves but don't have any browning or yellowing. I'm not sure what the issue is. For reference even the patch where I just put a root tab a couple weeks ago had the same reaction.
I can get more specs if needed, and I'll take a picture of the s repens later as well.

 

Excel is not a plant food. You need to feed your plants with a proper water column supplement. I use the Seachem line. There are six that I use: Excel, Iron, Potassium, Advance, Trace, and their root tabs.

I prefer this over the all in one supplements as it allows you to dial in the supplements to the plants needs rather than throwing everything at once at them. Also you want to use the organic and inorganic on separate days. As I understand it there is a conflict between the two. You can not do this with an all in one.

Just my two cents worth.

 

I was afraid that might be the case. I know that excel doesn't have good macros, but I was hoping with the root tabs I'd be good to use up the bottle before getting Aquarium Co-Op's Easy Green. Any ideas what nutrient I might be missing that would make it suddenly drop leaves? All my other plants are still doing great and growing quickly.

The s repens ended up losing the rest of their leaves a couple days after I posted this. They look like this now.

 

My S. Repens just recently did this also, I only had them going for just around 2 months and they were so thick and healthy and pretty looking, suddenly shed every leaf within days, healthy green leaves floating everywhere, I've seen so many different forums and people that had this happen also but nobody seems to really know why. Also planted in fluval stratum and dose Thrive S liquid occasionally. Cheap full spectrum lighting, it literally makes no sense how they can be doing so well then just like that bare green stems everywhere.

 

I posted all this in an aquarium plant specific forum as well. I was told it was probably melt back and the leaves would return as long as the roots look healthy. Currently, the roots still look great but not a single leaf has returned.
I switched weeks ago to Aquarium Co-Op's Easy Green. All my other plants are still doing awesomely and I'm considering getting some new s repens cuttings but I'm not sure if it'd be a waste.

 

I think the temperature change is minor but you did reduce the light by 25%. That is quite a bit. It could simply think it is fall. And you "switched weeks ago to Aquarium Co-Op's Easy Green", so I wonder what the s repens could need that the other plants don't.

 

I think the temperature change is minor but you did reduce the light by 25%. That is quite a bit. It could simply think it is fall. And you "switched weeks ago to Aquarium Co-Op's Easy Green", so I wonder what the s repens could need that the other plants don't.

That's the thing I've been wondering. I checked my order date and its been over a month using the new ferts.
My multiple anubias, java ferns, sword, lotus, hair grass, marimos, christmas tree and java mosses are all doing well and need regular pruning.

 

I think the temperature change is minor but you did reduce the light by 25%. That is quite a bit. It could simply think it is fall. And you "switched weeks ago to Aquarium Co-Op's Easy Green", so I wonder what the s repens could need that the other plants don't.

Hmm... could be on to something there, I also reduced lighting bc of brown algea (diatoms) but that was quite awhile before the leaves decided they didn't want to live anymore. However before all leaves were gone and there were still a few left I cut every stem to about a half inch to 3/4 tall taking out what leaves were left before they shed and I now here we are weeks later and im seeing a number of tiny leaves starting to grow, seems like it's going to take awhile tho and probably never get back to how they were. Mine were tissue cultures that I started with and I knew I'd get some melt back when I submerged them but this was not melting but more shedding/droping and they had been submerged for 2 months and the light reduction well over a month before the drop.

Also just realized maybe it is something to do with the all in one ferts like Thunder o b said above about a conflict between organic and inorganic being dosed all at the same time? I must have not understood what he was trying to say when I first read it. Just hate not being able to figure something out lol drives me nuts.