I was under the impression you needed high/strong lighting to run co2
With the species you’ve selected they’re mostly slow burners. This tank is of a similar depth and also has low light species, it has point source lighting and a measly 10 PAR at the substrate:
EI with high Co2 and low light works.
The bolbitis in your photo from December 2020 already showed severe blackening of the leaves.
Your Pinnatifida was stretched and is one species that doesn’t fit in with the rest of the planting, mainly because of the light requirements to keep it being at odds with everything else. You could attach it to wood high up in the scape to take a punt, but it isn’t guaranteed to work. Pinnatifida is a whole over subject though.
You have jet style outlets so covering the surface with floaters to lessen the light might blow them about a bit. You could drop down to just the tubes or the Aquasky and get Co2 dialled in.
Is that drop checker light green at lights on? Is there improvement to be had in the ramp up and/or injection rate?
Surface agitation may be high between the jets and the eheim skimmer. Is this gassing off Co2 too readily? It could be fine as is, what is your current thoughts?
The plant mass is generally low. You also have a decent amount of stock including some chunky SAE’s. Are you overfeeding your stock?
Maintenance... got an electric toothbrush? You could brush all the BBA off of those rocks. An alternative is ADA Phyton-Git Sol. Switch off your filter and syringe it over the affected surfaces and leave for 10 minutes. It will be dead and if the BBA on the rocks is soft enough, your SAE’s will eat it for you if their feeding has been reduced. Otherwise, scrub and siphon out.
Water changes... definitely a friend through periods like this.
Estimating that the core problems are too much light, inadequate Co2 regime, large amounts of organic waste from fish and decaying plants, inadequate oxygenation across the 24 hours as your plants aren’t performing.
Remedy wise, lessen light, tune in Co2 to an optimum, evict the BBA, water change the system frequently for a while, monitor new growth and reduce feeding to a minimum temporarily.
Additional measures could include:
- cutting out leaves that are beyond redemption
- making sure rhizomes are secured to hardscape appropriately for your epiphytes
- seeing if anyone on the forum has spare plants they can donate to get things rolling
- running night time aeration from lights out to just before Co2 clicks on
You want ample o2 for the system to work, this comes from plants and gas exchange. Running night time aeration during periods of trouble ensures the tank is getting a constant top up to atmospheric equilibrium throughout the night - effectively more o2 than demand. Filter benefits, plants benefit and livestock benefit.
Given you have all that sand real estate available, you could consider temporarily planting out Ceratopteris Thalicroides (water sprite) around the perimeter in the sand. Cheap as chips, it grows aggressively and will work as a great oxygenator in the interim.
