yes my ferts have been low but it seems the more i give the worst the problem gets i am using ionic grow usually for hydroponic but have had success using it in soil its a low salt residue .i have a freind who is using with high salt and same strand and he is haveing no probs
Flush your plants with just water and make ph around 5.5 leave them to dry out then say at the same feed has you have been doing if it carrys on up the nutes alittle.I also put some sea weed exstract around my plants if yr growing in soil this does work give it a couple of days to kick in i think it's the nitrogean content.
when the water dries the acidity should increase a little..... its easier just to aim for 6ish.... as for seaweed, try kelp extract (the same stuff) its much easier to handle, and organic!....though any fert with n-p-k and a good micro nute support (like iguana juice) should work 100%