Need help with humidity. Anybody know how to raise it.

Hi everyone i started my 2nd grow 2 weeks ago and i have very low humidity and my seedlings are growing slow and i think low humidity is the problem. The same happened with my first grow but once they got to the 4th node they started growing really fast.

first off what is low 10-20 or 40-50 ?? its need to no info to get you your answer.

I'm growing in a grow box under 170w blue spec cfl's and strains are 1 x white widow and 1 x aurora indica. I read that putting a bowl of warmish water in there can raise humidity.

A bowl of water with a sponge floating on top works real well.

Would it be worth changing the ph of the water before making it float in the air

you mean before making it evaporate?

good question, but I've never heard anyone do that so i assume not...

It's working well the water level in the bowl is getting lower, I don't have a humidity tester yet but i know from my last grow that humidity was low cos the leaves were getting really dry but got away with it and was nice smoke.

A bowl with rocks in it underneath will work well if you can keep it topped off every day. I do this with my clones I'm hardening off. Just grab a glad container and fill it halfway with lava rock. As it evaporates off your rocks it'll keep it humid around the plants above it.