1 or 2 per week if the substrate is inert.
Every day to every 3 days if the substrate is a buffering one like Aquasoil / Tropica soil, but follow manufacture recommendations.
It mostly depends on fertilizing regimes and stocking levels.
Rich fertilizing = more water changes needed.
Your cycle will progress a little slower than usual, however it will still happen without issue. Ammonia at your pH will be mostly all in an ammonium form which is much less toxic.
Your substrates buffering ability will be shortened with large water changes, frequent water changes containing...
The Tropica soil is lowering your KH thus lowering your pH.
Your wood is also lowering pH.
The soil is purpose made to do this. It is perfectly fine to use it the way you are using it.
Over time, it will lose it's ability to buffer KH thus pH and your tank water will return to your tapwater...
What is your substrate?
Do you have any driftwood, peat or anything else in the tank that will lower pH?
Do you know the KH of the tapwater and tankwater?
Set a glass of tapwater out for 24 hours and then test pH. This will give you a much more accurate pH reading. Tapwater pH readings...
I would certainly consider going with CO2. If the main focus is going to be on the fish, running CO2 at a slightly lower, consistent level will allow for great plant health without risking any gassing of livestock.
You could also run controllers (like a pH controller) to add some redundancy...
99% sure it's CO2 build up in the tapwater - as everyone else has mentioned, let a glass sit out for 24 hours, it will most likely off-gas the CO2 and have a pH of 8.2.
My tapwater is the exact same - 7.4 fresh and 8.2 degassed.
pH swings from CO2 are harmless because you aren't changing...
When we say "clean the filter" we really mean remove all the free floating organic material in the mechanical media (sponges) and gently rinse off any biomedia in old tank water to free up more surface area the organic material is plugging up.
The only thing that should be replaced or...
Did you changed your filter media completely?
You ran chlorinated water in the tank prior to adding Prime?
Was the tank cycled / how old is the tank?
Those tabs are mostly inert filler material and contain very little nitrogen, so it was not the tabs that are causing your parameters to spike.
It's not Rotala indica. Rotala indica is mislabeled in the hobby by most plant suppliers.
Ammania bonsai / Rotala bonsai is the true Rotala indica.
The mislabeled Rotala indica are just variants of rotundifolia.
I'll go out on a limb as say go DIY.
KNO3 - For NO3 and K
KH2PO4 - For PO4 and K
K2SO4 - For K and S
CSM+B - For micro's
DTPA 11% Fe (if your pH is higher than ~ 7.0) - For Fe
Flourish Iron (if your pH is higher than ~ 7.0) - For Fe
CaSO4 - For Ca and S and GH
MgSO4 - For Mg and S...
I do not recommend trying to separate it. There isn't an easy or "good" way to do it.
My experience with Stratum is it turning into mud as soon as I tried to physically move any of it.
Decide which substrate you want and go with fresh stuff...