4 questions, opinions/advice much appreciated

[LazyDays]

I hope my questions are clear, my brain has melted a little trying to find these answers, so if anyone can help, I'd appreciate it very much!

Strain - Indica DNA 60 Day Wonder auto
# of Plants - 4
Grow Type - Soil
Grow Stage - Vegetative? (3 weeks from seed)
Bucket Size - 10l
Lights - 1 600 Watt HPS dual spectrum (not dimmable)
Nutrients - Biobizz, only given root juice in distilled water
Medium - Biobizz allmix
PPM - ?
PH - ?
RH - >20% to 61%
Room Temperature - 28-40C (83-104F)
Room Square Footage - 4x4 grow tent
Pests - None Known

Question 1: Where does the hygrometer go?

I can't find a definitive answer for this one, some say at plant level, others say away from the light, so I don't know. At the moment I have 2 inside the tent. I've put 1 in the bucket with the plants directly under the light, this one reads 33-40C (91-104F) RH 20-30%. The 2nd one is about 6" higher than the buckets and about a foot away, this one reads 27-29C (81-85F) RH 50-61%. So which is the one I should pay attention too?? Either way it's too hot.

I've been hanging 2 wet towels either side of the light at bucket level to raise humidity, these are dry within 4hrs and if I'm at home I'll re-wet them, if not, I do it as soon as I can (I've ordered an ultra sonic humidifier to do this job more efficiently I hope!). I've also been leaving the mesh vents uncovered to try to get more cool air into the tent.

Question 2: How do I fix this heat problem?

I have a 600w light in an air cooled 5" cooltube set up like this: 5" TT fan outside tent > ducting in through lower sock > cooltube > ducting out through higher sock > Y piece to connect with extraction fan > vented to another room. Extraction fan set up like this: Carbon filter (not attached yet) > ducting out through top sock > 5" TT fan > short ducting > Y piece > vented to another room. Also have a tower fan inside tent, and a desk fan blowing into a cooler box of frozen bottles and ice which exhausts gently over the plants (not very effective to keep things cool but does add humidity). I don't want this contraption to stay in the tent, it's a means to an end at the moment but takes up too much space and I can't keep up with the ice supply lol.

I've been led to believe that it's better to have cool air 'blowing' over the light as opposed to 'sucking' cool air over the light, but I've been wondering if it would indeed be better to re-position the fan so it's ducting > cooltube > ducting > fan > ducting to Y piece > vented to other room. It's going to be a pain in the butt to change it around, so if it's not going to make much difference, I'd rather not, but will go with any advice given.

When I initially set up my tent, I didn't have enough ducting for the extractor fan so just dropped it into the top extraction sock and tightened the cords so it wouldn't fall out. Suction was great like that, really pulled the sides of the tent in, but since I've attached the ducting and vented it out of the room, suction has fallen dramatically (however humidity has slightly improved) and I imagine that once I have the carbon filter attached this will decrease even more. So I've been thinking about getting a 6" RVK fan for extraction, and using the 5"TT fan to blow cool air into the tent but I'm coming to the end of my contingency fund, and I don't want to keep throwing money at problems if it's not going to solve it.

Question 3: Should I leave the fans on during the dark period?

I have the fans running 30mins extra after lights out to cool things down. Once they're off, temps drop to 19-23C (66-74F) but humidity climbs to 90%. Should I just leave the extraction fan on or should I also leave the tower fan that blows over the plants on too?

Question 4: Best way to change the light cycle?

I have lights on from 6am-12am. I really should have taken more notice of advice to have the lights on at night when it's cooler during summer. I want to change the schedule for the lights to be on from 5pm-11am. But, if I have the lights on during the night, I won't be able to leave the mesh vents open, because I won't be able to sleep with all that light! So that may be a problem with my existing heat problem... I was planning on changing it gradually, leaving them on an hour later and waking them up an hour later every 2 days until I'm at 5pm-11am. Is there a better way to do it?

for reading and I hope someone can help with any answers.

 

[Regor]

Question 4: Best way to change the light cycle?

I have lights on from 6am-12am. I really should have taken more notice of advice to have the lights on at night when it's cooler during summer. I want to change the schedule for the lights to be on from 5pm-11am. But, if I have the lights on during the night, I won't be able to leave the mesh vents open, because I won't be able to sleep with all that light! So that may be a problem with my existing heat problem... I was planning on changing it gradually, leaving them on an hour later and waking them up an hour later every 2 days until I'm at 5pm-11am. Is there a better way to do it?

Can answer #4 - Do the light change by just leaving the lights on until your ready for the new dark period. The extra light will not hurt her, as some leave their lights on 24 hours a day.

 

[LazyDays]

Thanks Regor. With the heat problem I'm having and they're so heat stressed already, I don't want to leave them under the light any longer than I have to, so I'm going to do it with a 2 hour change everyday until they're lights out at 11am.

Been doing a lot more reading today, no closer to the answer for question 1 ~ hygrometer placement, but the consensus seems to be to have it as close to the plants as possible, under the light or in the hot spot, I'll still have 2 but this is the one I'll be attempting to get under control.

For question 2 ~ heat issue, I learned loads about cfm and cm3/h today and I eventually found an equation that answered my question, not sure if I can link to another grow forum but if anyone wants it PM me. My 5" TT fan isn't strong enough so I'll be using that as an intake fan and I've ordered a Ruck RK150L which will be controlled with a plug in speed controller for extraction. All my ducting and vents are 5", so I'll use reducers to connect it. I'm hoping this is the last big purchase I'm going to have to make and if it doesn't solve this heat issue, I'll finish this grow if I can, and pack it away until winter.

I'm going to leave the cooltube set up as I have it with the fan blowing air over the light, but I did learn that I have far too many bends in my ducting, so I will be fixing that tomorrow and making it as short as possible. I've also put the cooler box contraption outside the tent, with it's exhaust blowing in through one of the lower socks, this has helped drop the temps by 2C

For question 3 ~ still found mixed answers, but more seem in favour of leaving the fans on periodically during the dark period. So I'll have them off for an hour and on for half an hour and it fits neatly into 6 hours

Hope this helps anyone else, and I really hope the new fan is going to solve my heat problem. Will report back when it's all up and running.