Its either the compost is too hot in your perlite mix or theres too much nitrogen and or the ph in your fish tank water is messing up your soil ph causing nutrient lockouts trust me I have both grown in and with STRAIGHT ORGANIC nutes and soil as well as with atm synthetic nutes with coco coir I know my stuff,do you ph your water/soil/run off? Now I used to use a combination of bat gauno worm castings and molasses it did the trick all year round dont get me wrong I had sum mad fuck ups but I learnt fast bro you name the deficiency I made it happen with my first couple grows,with the exception of getting root rot.are you giving them any calmag? Dolmite lime and magnesium from the supermarket with do the trick less is more tho bro,oh and undecomposed compost will reak havak on plants always pay for quality,cheap stuff will destroy a grow in no time