Thank you for all the suggestions. I really did not consider the lack of circulation possibility.
My filtration consists of a sunsun 303 filter but the spray bar directs flow across the tank with the affected anubias beneath it. So they really don't get much flow in their current position, ie more indirect flow then anything. I have been considering adding a second canister and have the spray bar on the opposite side so this would be a perfect time.
I suppose the frequency of WC's is just me being set on a schedule. I would probably be a perfect candidate for the EI method! I have noticed that both my fish and plants seem to 'perk up' after a change and the few times life has gotten in the way and I've had to push back my WC schedule to 2 or 3 weeks my tank just looks...off (both the fish and plants). I also have a small population of snails and have to keep up on siphoning their droppings otherwise the sand gets dirty looking.
I looked at the Seachems phos that was recommended and it's listed as potassium phosphate. Much of my dosing has relied on premixed solutions (excel, thrive, flourish comp, etc.) so I would like to try my hand at mixing my own. A 1lb bag of powder potassium phosphate from nilocg is $5 so not a bad start for a first time mixer. As with the Seachems I'll have to figure out the correct dosage through dosing and testing. But thank you for the suggestion!
A recommendation to increase Thrive to 3X a week was suggested. Would there be any drawback by increasing both the macro/micro nutrients it delivers? Up to this point I have not made too many changes to my dosing regimen, thus my slight hesitation. I guess my worry is an overrun of algae due to excessive nutrients - just me being a bit paranoid!
Thanks again for all the suggestions!