This is going to be a long update - I am running into a few issues with this scape and it looks like the reason is random ammonia spikes.
Some factors which might be relevant here (in the sequence)
Soil - I have used Aquario Neo Plant soil in this scape. I didn't appreciate just how easily it breaks and I ended up crushing a lot of it while playing with hardscape.
Filter - The scape is powered by Oase Bio Master 350 and two chambers are filled with Aquario Neo Pure bio media and two with sponge.
Dark Start - I kicked of this scape with a dark start BUT made one crucial change. For nearly a month or so, I ran it at a significantly warmer temperature (30-31 degree c) with an intent to help nitrifying bacterias settle. I was also dosing extra Seachem Stability at this point to help cycle the tank and in two weeks or so, the nitrites were 0, and ammonia was about 5 ppm and nitrate was about 5ppm. Diatoms bloomed and vanished by the time I started planting.
Root Tabs - After nearly 1.5-2 months of the dark start method, I lowered the temperature to 23 degrees and planted this tank with Starygyne Repens, Pogostemon Erectus (Both Tropica Tissue Culture) plus Rotala Colorata and Ludwigia Sp. Super Red (These two were sent by friends and were held up in the post. When I planted them in the tank, the tips were nearly dried out so I assume they were quite damaged at this point). I started dosing APT Zero (Non-NP fert) at this point but noticed that plants were growing remarkably slower than they ever have in any of my other scapes. Upon checking the parameters, I realised that nitrates are almost zero so I decided to add some Aquario NPK root tabs (1 tab in every 4 square inch area) with an assumption that running the scape at 33 degrees for prolonged periods, exhausted the soil of nutrients.
Fish Meds - With plants, I also added about 4 rescued mollies in the tank and they were suffering from the worm infestation so I decided to treat them with Esha NDX. I did not follow the instructions and left it in the tank at the recommended dosage for 72 hours instead of 24. I noticed the diatoms bloom after a few days. Since then I have dosed seachem stability almost on daily basis and have done 33-50% water changes twice a week.
At this point, it's nearly 3.5 months since I started this scape and the plants are showing severe Nitrate deficiency (stunted and discoloured tips). I have switched to APT Complete (2ml a day) and that has improved the growth to a certain degree but the plants are still very much struggling. I have measured CO2 by ph meter and it shows a full 1-1.5 point pH drop. CO2 is inline but to ensure that distribution is even throughout the tank, I have placed the drop checker at different points and observed that it does turn light green/yellowish-green throughout the different spots in the scape.
I use RODI water and remineralise it with SaltyShrimps GH+. Current Gh/Kh is at 9 and 8 respectively. I suspect the increased Kh is due to seiryu stone in the base.
I am suspecting that the main reason why I keep getting diatom blooms is Ammonia spike and I am trying to find out why is it happening. I can't see any reason why my cycled would crash and remain crashed. It has about 3 litres of bio-media (the same media is working amazingly on my 45p which is stable as a rock) in a fairly powerful bio master 350, it gets a dose of Seachem stability almost on daily basis at this point and I've never skipped a water change.
I am suspecting that one of the root tabs could have come up near the surface and could be causing random spikes in the tank? Or could it be accumulating as a result of extra dosing of APT complete?
Either way, I am super confused and could really use your thoughts.
@CooKieS @Geoffrey Rea @Courtneybst
Diatoms covered S. Repens and P.Errectus in the right most part of the tank (this area has the highest flow and the highest amount of diatoms. The photos are from phone so not the best quality but I have ensured there is no BBA in here, this is diatoms only and comes off when I gently rub the leaves)
Top view

P.Errectus on the other side of the tank is doing surprisingly better than the one on right.
