Your help please

Well my system is up and running i have four plants in a flood and drain and a duel spect 400 w hps.The plants are only 4 weeks old.And the light is about 3 ft away.I lowered the light and burnt the leaves they went a yellow colour
and some of the smaller leaves shrivled up.Will they be ok they are still growing.
How long should i flood it for and how long should i keep it dry ?i have had it on 1/4 splells..and also i'am a bit concerned about the temp of the res,i,am using a heat mat and its been on 24 7.When i went to check it before the temp was at 33 c it felt a bit warm to say the least..What temp should my res be?

And also iam using a black cover but light is still hitting the top of my rockwool cubes and ive noticed algea on all 4 ive took it all off now,, is this ok? they is no algea in the res.
also would it be better to have a moving fan and get light closer or should i wait till they are bigger.

I really apriaciate all the help you's give.

Thanks inadvance cron

does no one know these questions i need help my plant are gona be rubish

ok I have 2 plants and 4oow hps too i have the light about 9" away closer is better but if too close it will burn I noticed when you turn the plants often they dont stress so much, a fan is good but make sure it is not contributing to heat if on all of the time. you should see after a couple of hours the stress starting with yellowing of the leaves(edges) if you move it then the plant will not be to bothred i have heat stressed my plants quite a few times and it got over it..85 is too high without extra CO2.(i heard yeast and water pruduces co2) any way visit them get in about them more often , breath on them, hold your fan over the top them regurarly but if light is too hot get it away and find a reflector and/or cfl's for round them so you have more lumens around the plant. but i have a shitty little fan and 400w hps and got no problems. 3 feet away is gonna make your plants skinny and more likley to fall over under the weight of the flowers (or just die!!!). check out my thread(introduction) i have already asked most of these Q's, so if you dont find it there you can message me and ill tell you what ive done so far with so far real good results hope this helps
cheers