Wish i had a Marshydro fc 3000

Plants started looking sickly yellow edges curlews tips pillowed leaves on 1 and 2 were the worst. Checked soil ph with our cheap 3 in 1 probe and it read roughly 7.5 so then thought may have had nutrient lockout so decided to give them a good flushing. At same time I searched the web and narrowed my issues down to: light stress, nutrient lock out. ( I really wasn't 100% sure and still not.) We raised lights up from 24ish inches to 30ish. And started actually using ph pen and ph down to male sire water is n range. Things seem to b getting better but growth of all 5 seems to b slow. Hopefully things will improve further...