Newbie grower questions!

[Niadir]

Hi all!

I have been reading this forum ever since I found it, and I think I got most of the things clarified out from other peoples guides on grow cabinets but there are still some things I am still wondering about!

My stealth cabinet is 200cm high X 100cm wide X 60cm deep.

According to the calculations I have done a 400w HPS should fit nicely.

I was thinking of putting the passive intake in the bottom with some finely meshed chicken wire over it to keep insects out. (Not hugely bothered with insects where I am except during summer.) And also have power supply, the ballast for the lamp and such in the bottom beneath a plate of wood.

The things I am wondering about is the fan and the carbon scrubber.
Now I have read alot of places about negative pressure inside the cabinet and I am still unsure of how this is done, I am also unsure about calculating the size of the passive air intake, fan size and carbon scrubber size.

I were also thinking of getting a cooltube along with the HPS but I have heard it can create hotspots / lower the lux output of the lamp?

I am also wondering about PH, how much water should be used and how often. I am sorry if this have been answered before I just want my growth to be done nicely the first time.

Thanks in advance for any answers.

-Niadir

 

[sneaky101]

Neg pressure IMO is a good thing. It lets you know no smelly air is leaking out. It is achieved by proper intake hole size. A general rule is 2x the size of your outtake.

L x W x H = cubic feet/ how many times/minute you want air exchange. I think divide by 3-5 on that one for the needed fan cfm and then match the filters cfm, maybe get the filter a bit more cfm capable.

Any glass barrier is going to lower the lumen output of a lamp. Just another surface for the light to have to penetrate.

As for ph, depends on your medium. 5.8-6.5 depending on hydro or soil. Others may dispute that but that is a general range. And water when needed. If hydro, when the Rez gets low and if soil when the soil feels dry and the pot feels light(ER) than when you firtst watered, just make sure not to overwater, especially when small. You will get the hang of it just by lifting the pot. Just pick it up once fully watered so you know what to gauge it by. Gl, hope this helps.

 

[dj_greenthumb]

Hey man, I'm a fellow noob myself but have learned a lot here so I'll try to help.

To start off, your cabinet is perfect for a 400w HPS. You generally want at least 50w per square foot.

Passive intakes are all you need. I think two holes that are at least 1.25x as big as your outtake is best. So if you go with a 4" outtake, have two 5" intakes. Remember though that can't let any light in or out so you're going to have to think of a way to accomplish this. Light leaks can ruin your grow very quickly.

You have just over 40 cubic feet in your cabinet so you don't need a big fan. Including the extra drag from your carbon scrubber, something that pushes 70-100cfm will be your best bet. You may even be able to find a duct fan that can push that amount for real cheap. If you want the best of the best, go with a Tjernlund M4; the quality is unmatched.

If you get a good fan, you won't need a cool tube because you're right, they lower lumen output. If heat does become a problem, you can always get one later.

pH is a big deal. Get some quality test strips that measure from 5-8 (at least) and test before you water and the runoff. Always aim for 5.8-6.2 but a little leeway can be given.

Water twice a week, or as needed depending on your plant-to-pot size. Have you figured out what kind of nutrients/fertilizers you're going to be using? I suggest "Lucas Formula" if you don't know yet... Google it.

Good luck!

 

[Niadir]

Hi,

Thanks for the swift responses!

The cannabis academy in Amsterdam (was a nice trip just fyi ) told me to go with sterilised soil and the nutrients that could be used for tomatoes could also most likely be used for growing weed. (The country I live in monitor things such as growth equipment and nutrients when they come trough the customs so slighty paranoid about that.) I do know the plants love Nitrogen during growth and phosphorous and potassium during flowering.

Only follow up questions I have now is how do I find out how large of an scrubber I need?

Also what is flushing and when is that done? I assume it is just stopping adding nutrients or?

 

[dj_greenthumb]

If you want to make one, you'll only need about 5lbs of carbon which sells for $30 at the pet shops around my location. Add in some mesh and some basic duct work and you have a filter for $45. If not, you can buy them online. For your cabinet, a 4" filter of 2-3 feet is fine.

Flushing is just watering with no nutes or fertz. It is done in the last week or two of flowering to get the chemicals out of your plants. You might also flush if your plants are showing signs of overfeeding or if they just look like they need some clean fresh H2O.

 

[Niadir]

Aha, thank you for a swift and nice write up!

Oh, and another thing what size of the pot should I aim for? The idea was to have three plants or four in that cabinet. Do the plants suffer from small pots? As in 18cm (7") diameter?

 

[Niadir]

bump

 

[Nader]

Aha, thank you for a swift and nice write up!

Oh, and another thing what size of the pot should I aim for? The idea was to have three plants or four in that cabinet. Do the plants suffer from small pots? As in 18cm (7") diameter?

3-4 gallons should work

 

[señorsloth]

i have a similar sized cab, i use a 190 cfm fan, wich is about 4 times the cubic feet of the inside of the cab. the rule of thumb is you want to refresh the air in the cab 2-4 times a minute, i went with 4 times a minute because the carbon filter can cut the output of my fan by half, meaning i'm really at about 80cfm's under the load of the carbon filter. i use a panasonic wisperfan for stealth, i think fans designed for this type of application(like vortex) don't lose as much power when hooked up to a filter, but i don't know this to be a fact.

the size of pots are usually determined by how many plants you want to fit into the area, if you are worried about plants being stunted by small pots check out some solo cup grows, people get 2 foot plants yielding up to an ounce in one 16 ounce cup(wich is a lot). that said i like to use the biggest pot possible, a grow bed. my cab is separated with the top 4 feet being bud space, and the bottom 2 feet are for vegging, i have two wooden boxes i built to fit the exact interior of the cab, about 10 inches deep. the bigger the pot the slower they dry, but the more stable the soil will be, meaning less ph swings and over ferting, however pots are generally tall and skinny, compared to a bed wich is low and wide, this means a large pot like a 5 gallon bucket will take a lot longer to dry out compared to a 5 gallon bed only 10 inches deep.

this is why people don't plant sprouts in 5 gallon pots, because it would take weeks and weeks to dry in between watering and can cause root rot and damping off. a 2-3 foot plant would be just fine in a pot that big because it can drink that volume of water. a bed however, with it's large surface area will still dry out weekly, despite being the same amount of dirt as the 5 gallon bucket, so it actually is possible to plant seeds or clones in the final sized pot, without risking root rot but gaining all the benefits of a larger pot, meaning more stable soil.

not to promote my own opinions too much, pots will work fine, but you want to base your final pot size on the final size of the plant. with a 400 watt hps anything over 2 feet is pretty much a waste of veg time(excluding vert grows), as the light only pushes down effectively about a foot into the canopy. if you veg an extra month and grow a 5 foot plant for instance, you will end up with 1 foot of quality buds and 4 feet of bare stems and popcorn fluff buds underneath it.

with pots you want between half a gallon to a gallon of soil per foot of plant. overdoing this in a pot can mean excessive drying out times, i usually recommend 2-3 gallon pots under a 400 watter just based on plant size but then again if you are only growing one huge, spread out lst plant or vert plants you could need up to 5 gallons. generally you want as much soil as possible while keeping drying times around a week in between waterings, this can be tough to judge though untill you have had a few grows under your belt. thats why i prefer soil bed growing, you get a large volume of medium, leading to very stable soil and still good dry times.

i use a cool tube and personally i think the whole cool tube arguments are hooey, i have never noticed a difference in my buds from side to side, comared to back to front. meaning if the tube acted like a convex lens of some sort, concentrating the light into a strip down the center of your grow, you would expect the buds would be uniform left to right, but not uniform front to back, meaning the buds in the middle would be denser than the ones in the back and front. i have finished 2 grows and am about 2-3 weeks into my third with my cool tube and from what i can tell the bud density and ripening times are pretty uniform across the entire canopy, no different than my old square type hood i used to use back in the day. i understand that this is not totally true, it does have the effect described, but not to the extent that you will really notice it in your finished product, and it has an added benefit of better flow through circulation. sort of a trade off, for me the main draw was that you can get an entire 400w cooltube kit with the ballast, cooltube, bulb and all the chords for about 150 bucks shipped on amazon.com. i know it's not the best out there but mine is a very sturdy setup and i'll probably be using it for years to come, it's already grown me over a pound of pot in 2 harvests so it's well worth the money.

 

[Niadir]

Thank you both for answers! And thank you Señorsloth!

 

[Niadir]

Hi all!

Sorry for updating my thread but I figured it was better than creating a new one!

So I just bought a digital pH meter and calibrated it so I could measure the water supply I have. Now that measures to 8.32 pH which after my understanding is way too much and I need to lower it. Is using something like this recommended? Do I measure the pH before or after adding nutrients?

Thanks for answers as always!