Potassium Deficiency?

[~firefly~]

I'm seeing the odd deficiency in my plants. To start with it was definite phosphate deficiency (test kits read 0) so I manage this with bi-weekly dosing of phosphates (managed with regular testing) and feeding frozen food more regularly (and feeding more). All improved dramatically, but now I'm seeing the beginnings of pin holes in hygrophila and alternanthera leaves. I'm assuming it's a potassium deficiency. I've recenly upped my lighting so this could be why. My amazon sword also has slightly transparent and misshapen leaves now.

After a water change, I dose weekly (full dosage levels for water volume) with either:
Sera Florena
or:
Tropica Plant Fertiliser

I tend to alternate each one each week.

I also stick in 6 root tablets each week Sera Florinette A. I try to put them in randomly (not in the same place all the time).

Daily the tank gets 5ml of EasyLife EasyCarbo, and 10-20 drops of Sera Day Drops (although I cannot find the ingredients for this which is annoying).

Any recommendations? I don't really want to have to dose something else as well but will look into any dosage recommendations or fertiliser changes.

The tank is 120 litres, heavily planted in ADA Malaya substrate, heavily stocked...and heavily filtered by an Eheim Pro 3. 24C. At the moment I do weekly water changes of 50 litres.

[Cermet]

If you are sure that it is a potassium issue, just pick up "No Salt" at the food store. Dose per recommended levels. Cheap and easy.

[biotsrama]

I'm a bit wary of the Sera Daydrops with the unknown ingredients. Personally I would not dose it if I didn't know what was in it. Just my 2 cents. At least with the Seachem line of fertilizers, you know exactly what you're putting in.

This might be a silly question, but have you ruled out snails as the cause of the holes?

[~firefly~]

Yep. I have assassin snails only so I'm sure it's not the cause.