Can plants have too much light

ive got 15 clones vegein at the mo, there are all about 10'' tall.
they were on one 600w hps and doing good, week later 2x 600w, a week later 3x 600w and started to turn yellow. temp is fine as i am using an air-con unit. oh they are in soil. Anyone know if im giving them too much light ( if poss).
CHEERS GROWERS!!

no, only too much heat..

in flower around the 3rd thru 5th week the plants exhibit some need of N...so in my feeding schedule i usually bump up the N for that week. then back off....

Its possible to get light burn, but in your situation its more than likely an entirely different problem, besides light burn doesn't present itself with yellowing leaves. Sounds like you either are over watering or need to get a bit more nitrogen to them.

Too much light the plants will turn yellow.