Hi, ideally this Q would be best for people using a homebox xxl as I have, otherwise anyone with knowledge please advise...

got an RVK 150mm L1 on the extraction pulling through a 150mm phat philter. intake is a 100mm TDS 250 pulling from outside. none of the lights are aircooled or anything. I put one of the 600's on and set the primair to 26 degrees. the temps rose to 29.5 and couldn't get any lower, and thats just one frickin light. I'm guessin the second light is going to bump the temps up to the low to mid 30's (unacceptable). Would you suggest I upgrade the intake to a 125 orrrrrr are we talkin about upgrading the extraction to 200mm and the intake to 150mm. I plan to run some co2 through the place with a unis so that means i could accept about 28 degrees max right? keeping in mind the warm days that might be approaching.

advice is needed people.

Many thanks

A friends set up is an XXL bud box, two 600w in parabolic shades, 200mm RVK with matching filter out 150mm RVK in. Runs sweet as a nut.

One question would be is where are you measuring the temperature within the tent? Try taking several readings from different areas of the box to give you a better idea of the general air temperature. Having the sensor in direct light can for instance add a few degree to your temperature and give you a false indication of the actual conditions you will be growing in.

29 degrees was out of the direct light. and slightly beneath the height that the plants would be sat at. so did he have to slit holes in the tent to fit the 200mm through?

with co2 you can hit temps of over 30, have had temps at 35 with aboslutely no problems at around 1700ppm. but you can't run co2 and have your ventilation on, especially not with a unis, so your temps will be way above 30 with the ventilation off.

personally i wouldn't bother with a unis anyway, they're not accurate at all and you have no idea of the actual co2 levels in your room, and you can pick up a telaire ppm monitor for 50 notes which will give you proper ppm accuracy

the thing is, my mate kinda jus gave me all this equipment to use, so its not like i have to fork out for it. would you still not bother using it when the fans are on? if my fans will be running 24/7 does that mean its passive?

The bbox has big enough holes to fit 200mm ducting through, though it was a struggle as we used acoustic which is a tad over 200mm, but it will go through.

do budbox and homebox have the same size holes?

I have two 600W hps. Link for me diary is below in my sig. Unfortunately I'm a yank so al of my measurements are US standard.

good luck!

we say passive intakes when you have only an extractor fan and no intake fan.

there's no point adding co2 with the fans running because it will just get sucked out, the unis works on a timer system, so it'll dose in co2, and be sucked out long before the unit replenishes it, it costs about 30 quid to fill a 7kilo bottle of co2, in a proper system with aircon and no vents running, in that size tent this'll only last a week or so, dosing it in with the ventilation on is just throwing money away, you could set it up so that the fans go off for say ten minutes while co2 is dosed in, fans come on, vent the heat/stale air, then cycle the co2 back on and you should see a fairly good boost in growth, a lot of hassle though, and for a little more effort you could do it properly. best to get a good few grows under ya belt before you fuck around with co2 anywho

This man is wise and is your friend.

I appreciate the friendly advice honest, its just I cant see how its such a head f**k to use, i just set the volume of the room in the unis and hey presto. are there side effects to using it if its not used properly? even if the fans suck a lot of it out, surely it must be beneficial???

To be beneficial you need to maintain a certain ppm (at least 1200) in the atmosphere. With fans running this is difficult.
Also you shouldn't run CO2 at night.

CO2 enrichment makes plants grow bigger, faster. However if you do not have every other environmental condition dialed in (proper air, compost, water, nutes, etc) than it won't work. At best. At worst you could spend a lot of money for nothing and perhaps ruin your crop.

It seems to me that you are not that familiar with growing herb. I strongly suggest you get very good at it before adding CO2. Do a load of research (Uk420 is a great resource for that) and really learn how to grow well. As you are doing this you can learn about CO2 as well and how to best incorporate it into your grow.

I have a controller with CO2 fuzzy logic control, yet am not using CO2 until everything else is perfect. It took me about 6 months of cruising here at UK420 before I got me compost sorted.


good luck!

I know what your sayin and I know youve got my best interests at heart. you said you have to have all the other factors sorted before thinking about co2, so say for instance a beginner started from seed and managed to control all factors through the veg stage and flowering was about to commence, would you still suggest to leave the co2 alone if he has the equipment to hand already?

I would wait until I felt completely comfortable before adding CO2. There are soooo many factors to dial in and get right. If you have never grown before AND you feel very comfortable growing, something is wrong.

unless you can control temps with the ventilation off you're pretty much just pissing in the wind, the unis is basically a glorified timer that just doses in co2 every x amounts of minutes, the unis adverts neglect to mention the fact that to do it properly you need the:

JCO Unis controller
The beauty of the UNIS CO2 system is that it incorporates it’s own built-in CO2 timer so that all you need to do is dial in the size of your room and it does the rest for you. However, it doesn’t co-ordinate your extraction once the CO2 has been released. Well, the answer is to buy yourself this JCO Unis controller, which will co-ordinate CO2 release with extractor operation. This means while the Unis is releasing CO2, the controller will turn off the extractors, for a period set by the grower, to allow the plants to absorb the carbon dioxide. Comes with full instructions.

another 90 quid, could've bought TWO ppm meters for that much!!

thing when you're growing with co2, the plants grow much faster, things happen MUCH quicker, a nutrient deficiency that would normally take a plant over in a few weeks can happen in a few days, light bleaching is incredibly easy to do, humidity becomes a problem along with mould if you don't have some form of de-humidification, etc. all sortable, just a simple timer and relay circuit will toggle between the fans venting and the co2 dosing, which should at least help with temps and humidity, but with the fans on constantly you really are just throwing money away, with 1200w you wont be short on bud anyway!!! as for controlling it through veg, in veg is rarely when the problems begin anyway, you shouldn't really even ever need to feed the plants in veg if you're potting up correctly, problems (i.e. deficiencies, burn etc) generally start to rear there heads about mid flower. if you just plug the unis in and set it to whatever, you'll probably see a bit of improvement in your plants, but nothing amazing, and nowhere near the worth for the price of the gas

hi conflo,

listen to above posts, leave co2 alone until your enviroment is correct and your confident.

i use 2 x 600w hps inside a darkroom dr240 (2.4m square)
during summer months i need 10" extraction and 8" intake fans running at max most of time.
also extraction running 24/7 and have de-humidifier during off period just to maintain temps and humidity.....

trust me dude get your standard setup sorted before venturing out

good luck with whatever you decide..............tcc

hi, i have budbox xxl, 2 600's with 6''intake an 8'' extraction with a cf and i'm struggling with temps at the moment, i've over 10 grows under ma belt and i still wouldn't think about co2. if you keep all your other paramiters right you can get great results

Given the temps you've got on one light, you would have to upgrade to a RVK 200 L1 for extract, and a RVK 150A1 for intake.

Guys a dont know how u's are struggling so much with temps, i'm doing a joint grow with a mate in an xxl budbox n up until 2 nights ago we were running 2 x 600w HPS Parabolic Reflectors with a 5" High Powered Ruck + Phat Filter for extraction with the 5" Low Powered Ruck for the inlet n the temps below canopy at pot level were nearly always between 70-76F with temps at the top of the canopy at about 74-82F and a light level which is about 18" above the canopy temps are 85-93F.

But the prob was we didnt hav negative pressure so we had to ditch the inlet n run passives n the temps have only gone up by 1-2F in every place in the tent.

I'm beginning to see where you guys are comin from, and randalizer your right my confidence at this point is not rational, seeing as I just cocked my recent seedlings. I mean you could read for donkeys years on this site and be very knowledgable but until u get a few grows under belt... i know what you mean.
I can use my 150 L1 for my intake right? and im gonna have to cough up for the bigger extraction.
Deffinately setting up a grow diary because the more I read on this site and the more I hear of other peoples grows the more I realise this ball game aint straight forward. Please excuse my novice attitude to the whole thing...

Co2's stayin in the bottle for now. one day maybe

Many Thanks

I,ve got almost an identical set-up to you mate, regarding lights and tent. the thing is my tent is in a converted attic room which gets quite hot in summer and cold in winter. I,ve seen your diary an i'm impressed mate to be honest, i'm considering buying an air con unit to cool the room does anyone think this will work, i'm interested to see what you think evans.