Solving slight humidity prob using lights to dehumidify

[click80]

I have slightly elevated RH in a Secret J. tent....im at about day thirty five of bloom and running CO2, two 3x6 flood tables, two 600s over each table, 24 plants each table in 6inch square buckets filled with and surrounded by h'ton on a bed of STG....

Okay me rh was climbing into the high 60s, sometimes as high as 71...but to keep it even at that point was involving a lot of time adjusting the vents and doors on the tents etc....and it was wasting too much CO2....i have one of the huge tanks and its not that costly but i dont like wasting anything....so i decided to put my fan exhaust (8 inch max fan) up to the bottom square tent vent and did the same with the intake with the exception of putting a Y w/a damper on it so i can mix what its sucking out of the tent with some fresh air....now keep in mind this is the fan cooling my lights and i was reasoning that the lights would take enough moisture out of the air to bring it down where i like my RH mid 60s....i was worried that some condensation would pop a bulb, so i put in some old hortilux's (real old) and that didnt happen...everything is working as i expected and im even saving on CO2...but i still have this nagging feeling i might be missing something....any opinions????

 

[Seamaiden]

Have you ever just let it go ahead and get a little high? I just deal with it and make sure I have The Toilet Bowl Effect going on in the room. I have had a recent, mild bout with PM, but have been treating diligently and consistently.

Are you finding condensation on the walls? It wouldn't occur on the bulbs, it would anywhere the warm air meets cold surface (bulbs ain't it). Door knobs, joints of insulation, near the vents, if it's sufficiently cold or humid that's where you'll find condensation. I haven't found that even the high 70s will create condensation, it's when it hits the high 80s on up and the weather's really cold out (basement area).

Sorry this isn't quite answering your questions directly, but if you're worried about moisture on the bulb I don't see how it would happen on the warmest thing in the room.

 

[click80]

No i do not have any actual condensation, i did at first because i like to let them cool down at bedtime...it just seems to give a little more resin production...but since the RH was getting high during lights on i was getting condensation when i let it drop...so i put a little heater in the tent and am keeping it at just a 5 degree F drop...

Also you have given me some advice about something that was bugging me....cant i just let it run a little high? i take it that you have with no ill effects? mainly i am worried about bud mold...i dont know what spores cause BM and their prevalence here in SW Colorado ...my guess would be it is not as much a problem here as in the Pacific NW....

It is not only bud mold I am worried about with high humidity, but since i am running co2, high humidity can become a limiting factor...its just that im not seeing any limitations...the kids are doing great...eating a lot, drinking a lot, ph is as stable as ever..slight fluctuations, but normal to me...they have got what i call their "second wind" or second spurt and are eating up about 80 to 100ppm of nutes per day, i am using Technoflora, so i pumped them up to the high 1700s and they are still sucking them up...roots are plentiful, and i mean PLENTIFUL, so all this says to me that transpiration and respiration is jamming along....

Granted i cannot say what they would be doing if i could stabilize in the 50s, but like i said they look great...no canoeing (that looks like its spelled wrong)...lol....but the leaves are straight, strong, good turgor, light orientation etc..

So yes I am going to run with it as is...i am able to keep the RH at about 68 to 71...

Once i get my CO2 generator back (i will never lend equipment out again) then i can put up my whole ventilation system as it should be...i do have a stand alone aircon w/dehumidifier that will take care of any RH problems i might have.......

Another thing that has bothering me...isnt RH in the 60 to 80 range good for vegging with or w/o CO2? If so then it seems that i will be okay as long as my ventilation is good, and it is, as long as i am vigilant about looking for bud mold......

sorry if this sounds like i am answering my own question and asking more, but unfortunately the only people i have to run stuff by where i live seem to love to just achieve mediocrity...and that is so not me...im OCD with a side order of perfectionism when it comes to cannabis..a lot of people do not seem to realize how wonderful a plant it actually is....

its so nice to talk to someone that actually knows whats what....thanx

p.s Love that name "the toilet bowl effect"....im guessing ventilation?? im sure its not about the Tidy bowl man....thanx again...

 

[Seamaiden]

I hear you, this last year I have been ALL about stepping up my game, not just 'making do'. However, I don't know anything about growing with CO2 other than what I've read, so I can't answer how allowing the RH to climb might affect efficacy in using CO2. My vegging area tends to be a good 10% lower RH than my flowering room, it's a wood box whereas the flowering room is sticked out and sided with plastic and rigid insulation. And so, again, I cannot adequately answer those questions.

It's important to make a distinction between ventilation (moving 'stale' air out and 'fresh' air in) and circulation, which is just movement of the air within the space. The toilet bowl effect is created through circulation. I have fans pointed at the lights, a large fan pointed at a wall and a box fan below it pointed in a slightly different direction. This creates a lot of buffered wind patterns and is my solution to not having any oscillating fans in the space.

Since I don't have an A/C or dehuey in these spaces I have to deal with conditions as they are. That means that, outside of temperature and ventilation/circulation air control, I'm not controlling it. This, of course, has consequences, pros and cons. Absolutely there is the chance that the plants will be more prone to becoming infected with molds or fungal infections. But, the Borg HATE it and I am positive that it was the consistent >65%RH that kept a Borg infection that had taken hold in my veg-table (a big raised box with lights inside) from establishing on my girls that were in full flower AND my first ScroG... yeah, wouldn't that have been lovely?

You can try, in such an instance, taking a slightly more proactive stance. For instance, you could incorporate a routine of prophylactic treatments, whether or not you actually see disease. This is not my preferred method for any living thing unless we're talking about utilizing immune system boosts (such as can be achieved through low doses of salycilic acid, foliars of kelp/seaweed, etc) or less chemical means, such as regular foliar applications of stylet oil.

Or, as I'm currently doing, just have everything on hand should an infection occur.

You see, I have had to strike a balance in where my capital outlays are going to occur. Power consumption is a huge capital outlay for me, and so were I to utilize dehuys and A/Cs to control every aspect of environment, that would be prohibitively expensive. While treatments like OxiDate can also be expensive, they only need be applied on an as-needed basis, whereas the power is an 'always' kind of thing.

 

[click80]

I totally am with you on stepping up the game and i dont want to fixate on one aspect of the enviroment if i am not see any negative signs.

I am seeing great results right now and the RH is staying right about 65%, it does climb to about 70% for short periods of time during floods...i rearranged my circulation fans and have a great toilet bowl effect going... that helped a lot...thank you very very much for that idea....

i am having to add a little over 5 gallons of H2O per day, that is a little over a quart per day/per plant.... i keep about 27 gallons in the res...i am also seeing about a 100-120 ppm per day drop in nutes...that is telling me that they are drinking,breathing and eating...and they look great...

I am getting ready to try something new...i know there is a lot of opinions about using molasses in hydro...i have spent the last 3 days boning up on my org chemistry and i also called an old school chum who is a Professor at VA Tech now, he is a published scientist and i respect his views. He told me to go for it.....although there are more benefits to using sugars if growing in dirt, i will get the same benefits as the nutrients that have the carb boosters....lot more to it but that is the easy answer...i understand the science, i have just been out of school too long to explain it that well.....

If you dont mind me asking what are your views on Molasses?

 

[Seamaiden]

I use molasses and malted barley extract in coco, which is considered a form of hydroponics (I consider it "soilless media", but it is not inert). With coco you can use it in a manner commensurate with soil, in something like, say, a hempy tub using 100% perlite, go easy is my best advice. Sugars sitting in a solution may not be a good thing, but that's my inexperienced opinion. Go very light, a fraction of what would be used in soil or coco. If I were to use 1tsp/gal for soil feeds, I would adjust that to 1tsp/5-10gals for anything that's going to stay in contact for an extended period of time, or sit in solution for an extended period of time. I know that both molasses and malted barley extract begin smelling a lot like beer when they're left sitting for any period of time (>24hrs).

My grandfather graduated from VPI. :D

Is your reservoir open-topped? Is it in the growing space? That could solve your problem right there, if you were able to get it covered up somehow, save you the trouble of having to top so much. Also, if you want to automate it you can look into how reefkeepers top off their sumps with fresh water as it evaporates off.

 

[click80]

wow...VPI...thats what it was called when my daddy went...in our family it was a requirement to attend Va Tech or UVA....we had bigger fam get togethers when Tech played UVA than at Christmas..lol

Yep, my res is sealed....i was using a botanicare that came with the flood table but switched to a $11 roughneck tote from Home Depot....made my cloner from the same...very durable...and CHEAP...

You are on the same page as my Professor friend on the mixture ratio...he suggested at most 1ml per gallon....and thanks for the advice....as with any nutrient...less is better in my book...i have heard horror stories about people using upwards of 2 tsps per gallon for reservoirs...i dont understand why some growers will use their own additives to save money or for whatever reason, but wont do the math or ask for help...there are plenty of people, like yourself, willing to help...

Its funny you mentioned reefkeepers....it was on a website maintained by a reefkeeper that properly explained how to convert PPFD to Spectral Intensity so i could make some sense of Bulb specs....so yes i will check on that...sounds like you do your homework also...:yes

Well gonna go mix up some molasses...

 

[Seamaiden]

Sanjay Joshi, perchance? Aquatics is my background, know a few peeps, have some experience.

 

[oglovinlife18]

you can just get gardens cure sh*t works amazing ....how does the co2 work in the tent is it effective

 

[click80]

Sanjay Joshi, perchance? Aquatics is my background, know a few peeps, have some experience.

yeppers....thats pretty cool..small world...very smart guy....good info....

Yeah these bulb companys are a little skimpy on info....his site on relating PAR-PPFD-Spectral Intensity let me grow the hair back i had pulled out of my head trying to get some straight info....

 

[click80]

you can just get gardens cure sh*t works amazing ....how does the co2 work in the tent is it effective

on a results basis it is very effective...if you dont have humidity probs...but even with higher RH i am still seeing fantastic growth...i am eager to compare this grow with RH in the high 60s to the next set of flood tables i start which will be outside the tent....I will have my co2 gen back by then....i have my tent in a garage that i insulated and sheeted in 6 mil plastic...with this situation a co2 generator will be better as i can pump out way more co2 and run my standalone ac and not worry about the little bit that will be vented outside...the ac unit has a dehumidifier setting...i have a big co2 tank but i still dont like carrying it in and out of house....it only costs about 6 dollars more to get the big tank filled vs 25 pound tank, but has twice as much co2...

hope that made sense....im getting ready to get some sleep...im on the same cycle as my plants...up at night, sleeping during day...kinda like it....get plenty of reading done...im getting ready to start some online courses in prep for going back and finishing a chem/bio degree....

 

[Bobby Smith]

I have slightly elevated RH in a Secret J. tent....im at about day thirty five of bloom and running CO2, two 3x6 flood tables, two 600s over each table, 24 plants each table in 6inch square buckets filled with and surrounded by h'ton on a bed of STG....

Okay me rh was climbing into the high 60s, sometimes as high as 71...but to keep it even at that point was involving a lot of time adjusting the vents and doors on the tents etc....and it was wasting too much CO2....i have one of the huge tanks and its not that costly but i dont like wasting anything....so i decided to put my fan exhaust (8 inch max fan) up to the bottom square tent vent and did the same with the intake with the exception of putting a Y w/a damper on it so i can mix what its sucking out of the tent with some fresh air....now keep in mind this is the fan cooling my lights and i was reasoning that the lights would take enough moisture out of the air to bring it down where i like my RH mid 60s....i was worried that some condensation would pop a bulb, so i put in some old hortilux's (real old) and that didnt happen...everything is working as i expected and im even saving on CO2...but i still have this nagging feeling i might be missing something....any opinions????

I don't quite understand how your RH is higher with your lights on than off - I always had the exact opposite problem, RH would skyrocket when lights went off.

No, you're not gonna pop a bulb at all unless you throw water onto it, because like SM said, those bulbs are way too fucking hot for little droplets of water to form on them (even if aircooled, although I guess theoretically you could do it, but you'd really have to be trying to break a bulb).

Anyhow, in the name of K.I.S.S., why not just get a little dehudifier (EDIT: or "dehumidifier", dar dee dar) and hang it from the rafters of your tent? Less CO2 wasted and less futzing around with your ducting, and would also let you run your RH wherever you wanted to (although 65% isn't that bad).

Just my $.02.

 

[click80]

I don't quite understand how your RH is higher with your lights on than off - I always had the exact opposite problem, RH would skyrocket when lights went off.

No, you're not gonna pop a bulb at all unless you throw water onto it, because like SM said, those bulbs are way too fucking hot for little droplets of water to form on them (even if aircooled, although I guess theoretically you could do it, but you'd really have to be trying to break a bulb).

Anyhow, in the name of K.I.S.S., why not just get a little dehudifier (EDIT: or "dehumidifier", dar dee dar) and hang it from the rafters of your tent? Less CO2 wasted and less futzing around with your ducting, and would also let you run your RH wherever you wanted to (although 65% isn't that bad).

Just my $.02.

yes if i were to keep just what i have now i would do something like that...and you are right im not seeing any probs with rh in the high 60s...

on my next cycle i am adding two more flood tables and moving all 4 out of tent into garage and moving my mothers into tent...its a four car garage...in about two months i will be adding in an undercurrent system so i am ordering a big dehuey anyday now....just have to decide on size...once i move everything out of tent i will be adding some 1000s, 1 for each table so i can put my VERY OVERPRICED Horti Super Blues to use...i def believe in MH light during flowering mixed with the two hps...

oh and my rh does go up at lights off...i you read back a couple posts you will see that i am running my intake on my 8 inch fan and the exhaust back into the tent via the bottom vents built into tent...i have just put a Y on the intake w/backdraft damper so i can adjust the mixture of intake air ie how much it takes out of tent vs how much out of garage air...with lights on i dont want to bring in too much fresh as it would dilute the co2...so i have to strike a balance...with lights off i can adjust the damper to bring in all garage air...but it still goes up to about 73...all the better to keep the Borg at bay....lol

I went with sea maidens advice and am letting thet rh climb...it hits about 70 during floods but comes back down...once i move everything out into the garage adn run the dehuey with the co2 generator and have a proper ventilation scheme in place i am really interested to see what the difference is in yield...i have always heard that with co2 u want your rh in the 50s....but i am seeing fantastic results at my higher rh....their drinking a lot, so transpiration has not slowed down that much if any...they are eating nutes like crazy and i have a pretty steady ph...im really happy....plus i have an awesome BBCheese strain...they look like little christmas trees, perfect colas...perfect for SOG...

Hey thanx for the .02 worth....i never turn down advice or opinions....i leave that to stupid people...lol

 

[click80]

solved, for me anyway

Thanx for all the replys. I had a long school lesson from a friend that teaches at Va Tech. He explained about a concept named Vapor Pressure Deficit. This is basically a better way to measure RH as there are cofactors included which is specific to every garden. One is canopy temperature, the others are RH and air temperature. I should mention that i use willow water and i guess that is prophylactic on a number of levels and that along with good circulation is hopefully going to keep me safe. So I am going to return my tent to normal and let it go to the low 70s, which is what prompted this thread in the first place.

Just an FYI, some of his students just finished a couple first semester projects. Mycorrizhae does help in hydro...anyone interested can pm me and ill hit u back, too tired to type now.

Also on another hydro project, they found that topping off with even 50% nutrients can cause near toxic nute levels to develop inside plants. Although they might not manifest to the eye, the near high levels can cause slower trans/respiration and some other stuff.

I always went by ppm and if after topping off the ppm had dropped, then i added nutes. I always stayed on the shy side of 50% so i guess i was lucky. I asked him if it could be that cannabis is a more forgiving plant. He explained that the research was on either a C3 or C4 plant (whatever) and that it was reasonable to draw the same conclusion for cannabis. Obviously there are other factors. I think that serious growers usually have an amped up game plan in use that does use more nutrients, but i am going to do my own experiment with my new flood tables and see for myself. I would be happy to use less nutes...and i my BBC moms give off great clones, god im lucky i got them, i should be able to get good results, they clone so easy, and transfer to RW great so i should be able to run a few side by side comparisons....another i am going to do is with silicon additive from my friend...no even on market....

Okay, im tired from flying to and from virginia, but strangely turned on by the pat downs by the TSA...lol...gonna hit the rack...

 

[Seamaiden]

Who was it that said to give 'em a little grind back? That was funny. This is some excellent information, although I've heard of VPD, I haven't really gotten into it in any depth.

Coming from saltwater, the thing about nutes makes sense to me, I would 'want' to top off with clean water only. But, with the salties I was into/caring for, the goal was nutrient poor, not nutrient rich.