Regarding my salvinia issue. Never really solved it as such. Pretty sure it wasn’t fertiliser burn as changing the way I dosed made no difference. The die off was worst where the plants sat on top of very dense curled up Vals on the surface but improved when some of the Vals were cleared and it also improved as the tank matured. It will now tolerate denser Vals better than before, but I still get a wee bit of die off if they get too manic. (Believe me they can get awfully busy)
So for me, it could be a lack of circulation to the roots or detritus build up as junk gets caught up in the Vals or AN other but not sure how much this really helps you I’m afraid.
Regarding your issues, my 5 pennies worth:
I know it’s not ur first rodeo so apologies if anything here is like teaching you to suck eggs but it’s just my take.
Looks like a large percentage of your plant mass is Monte Carlo, which is a bugger to clear/clean and does a great job of capturing any detritus and decaying matter (especially if flow is a little suspect) It also ideally likes a reasonable amount of light and it’s fairly keen on Co2.
Higher light in a new tank is a bit of an invitation for issues, as is inconsistent Co2.
You mention your Co2 drop after 7hrs but Co2 should be consistent from lights on to lights off!! (I might be misinterpreting this, apologies if that is the case)
You’ve also had new aquasoil which some plants can be sensitive to for a multitude of reasons.
As mentioned, processing organics from either the soil or from decaying matter all sucks up oxygen too.
The highlight for me here is that you are getting nitrites, which is ideally not something you ought to be seeing 7 weeks in and would imply that your bacterial colony is not coping with what is being thrown at it.
If it were me, I would either do what
@_Maq_ has suggested and pull the plants, put the tank into a dark start, let it cycle for a good while and then start again or, if that seems too harsh, pull the Monte Carlo, lower the light somewhat, add a whole bunch of of cheap rapid easy stems that will work with that lower light and let the tank cycle out that way for a good while before starting again.
I am not an expert, but I’ve never had an algae issue starting a tank out with lower light…..and on that basis, I’ve never started a tank with plants that want higher light.
My main high tech tank (with aquasoil) only had a two week dark start before planting, then daily water changes for 10 days, moving to twice per week for around 3 weeks and then to once per week. My low tech (with just 20% aquasoil to inert sand) I just threw a ton of easy fast growing stuff in and went straight to weekly water changes. (Not exactly following recommended practice)
…..But both were low light start ups (the low tech remains that way) and the only algae I ever experienced was a little gsa. I’ve had some further algae issues as I’ve increased light in the high tank but mostly specific to slow growers and all pretty low level so very manageable.
I think it’s often too much too soon that brings new tanks down and once the damage cycle sets in, it can be really tough to bring it back.
Could be simply that the conditions weren’t right for the Monte Carlo to thrive and that tipped the balance. Deterioration creates organics, that feeds algae and bacteria, causes reduction in oxygen, makes the system less hospitable, all of which causes more organics and so on….before you know it you are in a hole you can’t climb out of.
Letting the system mature somewhat before you ask it to do anything too challenging at least improves your odds….and making sure you have the right conditions and a good balance in place at the outset helps (good stable Co2, good flow, not too much light) That way the issues are less likely to run away on you like a steam train.
I really do hope you get it sorted and it doesn’t end up in the loft 🙁 what doesn’t kill us makes us stronger right!……so odds on, your next bash at it, is gonna rock!! 👍😊
