Need Help With plant Problem(Non Weed Hydro)

Hi guys and girls, I Know this isnt weed, but tbh I use most (if not all) My Plant growing info from My Weed growing and most things seem to be very common

I Have A Mint Bush that was growing awesome But has been showing some Weirdness Im not Sure If its low on Sulfur (Not sure why as ive been feeding her enough) Or If it may be light bleaching (Not sure why as its only got 4 23w Fluro bulbs on it at a distance of about 400mm From the top canopy. If any body can Give me suggestions id be very grateful.

Ps. i know the water and roots look a little brown, its not root rot, its because of the seaweed food i use (seasol) the ph of the water is around 5.5-6.0 but seems to drift up to 7 in a few days if i dont replace the res. I norm Replace the res every third day to avoid this.

PPs She has been under 24 hour light.

ur ph is the prob. a bigger rez is the best way to solve this... rule of thumb if it takes Xgal to flood the table the rez should = x times 2.

im not sure i understand(Im still learning hydroponics) This is a DWC. The Ph Is Set For mint. (Or so i thought) What do u mean by the Table?

Thanks for responding

He's talking about a flood table/flood and drain, it's a different type of hydro setup.

Your pictures look very similar to an iron deficiency in mj (yellowing from the top tops down, from the inside out), which happens when the pH is too high...and coincidentally, you said you have been having issues with the pH rising way out of range and having to adjust it every three days. You don't need to change out the whole res, just use pH down once a day to keep it in the correct range. You should try to check and adjust pH once a day.

Thanks, Yeah Ive Been Trying to set My Ph Just Below optimal Range To Keep Them happy(Using The drop test atm, I Have A digi coming), The issue with the ph down (Which i have) Is Trying to figure out how much to use. Atm What i do Is fill up a 9lt watering can and put in enough to get down to 6.0 plus the nutes and My Seaweed feed. Then I Just replace the whole amount. Do U Know Why Perhaps The Res Is Going up so fast? Is it normal? I Kinda thought (From what i have read) That The Ph Would raise When the Roots had Eaten what they wanted and left the salt, but ive barely got a root system going so id thought that would happen later.

I Have a Ph meter coming plus a tds meter of a 0.56 conversion rate(Is that Good?) Coming, Im Also Learning to Grow before i move my weed to hydro


Ps. Before i digress, Best Suggestion For iron defiency? (Obv i need to add some), but im not even sure where id buy iron buy itself for plants

Adding Some Random Snaps Of My Current Plant - Poor thing has suffered alot of heat stress, but still looking great For only a month into Flower.

Can Anybody Explain Why My Ph Would Shift So Much Each Day? The Root system is so minimal yet.