Feeding regime

Hey, this is my first grow, using a wilma pot big 4 with just clay pebbles, with canna aqua vega a and b. the plants are in little root riot propagation cubes and are 4 weeks old from seed. Just wondering how often to feed or too keep the nutes flowing ? Got three on the go at the moment under a 400watt hps, with plenty of ventilation and air movement, 2 of them seem very happy although the third is a little dry, and curling under with a few brown spots although very tiny and a little yellowing, I can't understand this as the other two seem fine ? Thanks

Sounds like you have one of two issues. if it's dry then the drip tube is clogged or not close enough to water the plant but don't think so. I think the drip tube has been right on top of the root riot cube. If the riot cubes stay wet all the time the airball will drown, turn yellow and die.

I have run drip from constant to 15 minutes every 4 to 6 hours. constant is kind of hard because of the airball problem. all other roots can stay in water 24/7. So watch those starter cubes. I would do 15 to 30 minutes every 4 to 6 hours. less when they are small. more feeding when they get big.

rule of thumb on the nutes in your rez. when you have replaced all thwater in the rez with top up water it is time to change. So if you have a ten gallon rez and you top up your rez one gallon every day in ten days you need to change your rez. do not not top up you rez. if you don't top your rez everything in it gets more and more concentrated. plus your plants piss off waste in your rez. change two weeks max even if they don't drink that much.

Thanks, this seems to be a debatable subject as I've asked 5 or 6 people this and the answer tends to be either a feed every 3-6 hours or constant recirculating? Still not sure. What is the airball problem ? What is an airball?

At the bottom of the main stalk at the point roots start. This forms a kind of ball of roots. This area of roots needs more air than water. If it stays wet toooooo long the plant starts to drown. Outside it can rain for 3 days, but much longer and problems start. Same with hydro. That's why with a constant feed you need to keep it over to the side of the airball. The rootball needs at least one hour of oxy to be good in a 24 hour period.

All other roots that hang down can stay under water 24/7.

Either way will work. Tweaking things for yourself is what it's all about. find a path, stick to it, tweak to change. This way it is much easier to look back and make tweaks or see what the tweak did.

Few weeks gone and all is good, changed nutrients and buried the feed deeper than the cubes so try get damp but dry out after 45 mins. The girls are looking spectacular! I put oxygen pumps in the Rez also to combat the airball problem and they seem great. These seeds are from some traveller guy from the 90s, apparently white widow but who's knows. How much bigger do they get by the end of flower, I'm guessing they're more indica than sativa because of how bushy they are but I'm unsure when to flower as I don't have much height, probably 3 feet max growth left to keep them at least a 12 inches away from the light (400 watt hps) more opinions the better ! Thank you

There you go. I was going to suggest feeding for 15 minutes on and 45 off. If you say your medium is drying out in 45 minutes; ?that is the perfect time to feed again. So run pumps 15 minutes every hour, when the lights are on. you will always be fine doing this. this is also approx. the way it is done in commercial greenhoues. I don't believe in constant watering, because the rootball does need to breath and your planys will love you for it.