What size holes for grommetts?

[RobbieGanjaSeed]

I've been living watching over my shoulder for a couple years as the cops were put onto me by a "mate" who lost his mind.

i've moved house a few months back and want to start growing again, but have sold all the old system.

 

I want to build what seems to most frequently be called a "Dutch pot" system.

It all seems very straight forward, just got one or two questions if anyone can help it might save me some strife and a few bux.

 

I need to drill holes for all the grommett connections.

Can anyone tell me what size hole I need to drill, to allow the appropraite grommets to fit into them, for a good water tight fit for 17 and 13 mm pipes? The bloody hole saw are 20 bux each so I'd liek to get the right ones first time if I could.

 

Also, I've seen this set up done two ways. One with a pot ontop of another, held together with a screw type arrnagement which doubles as the drainage for the pot itself.

I want to forgo the two pot idea, and raise the system up about thight high to save my aching back a bit of strife caused from bending. So I was going to use PVC (maybe 2 inch) for return to the tank, but this would mean drilling the grommetts onto the sides, rather than underneath, and I wonder if this will cause problems at all. i can't seee any, but someone told me it could result in excessive "stale" build up of nutes because of it's impossible to get the grommet perfectly on the bottom of the pot.

Personally, with the amount of nutes flowing through all day, I find it hard to imagine it'll go "stale".

 

Anyway, anyone see any problems with it being set on a table top, with the holes on the sides to a PVC pipe, I'd appreciate to hear the concerns. Thanks heaps

 

cheers

rob

[Pure]

Hey robbie ,

 

some grommets are different than others you have the double sided seal grommets which are most often seen on bongs and you have the one way seal one that look more like a very stumpy T shape if your usign the stumpy ones the measurements for the 13mm grommets is 16 mm , the messurement for 17mm I cannot be positive of but if they follow a pattern then it would be 20 mm ( as the 19mm ones take a 22mm hole and the 22 mm ones take a 25mm hole) if you wanted to confirm that though it should say on the rubber of the grommet that it is a 17mm grommet and needs a hole saw of ... mm ( i believe it is 3 mm greater than the grommet ) I run a modified dutch pot system myself and to ensure a tight fit for the grommets I drill the holes a mm less than advised and then I use a circlular file to take it to the exact size needed.

 

In regards to your other question , yes that is a simple enough task to do , Infact one of the modificatiosn of my own dutch pot style system is to leave about 2 inches of water in the bottom pot with an airstone running in there , this acts as a seccondary/emergency food source and seems to work a dream , once the roots get down there the water doesn't really last long enough to go stale it just acts as a seccondary sorce of food , if you are worried about it though it's just a matter of ballancing out your feeds to that the run off is enough to wash away a fair bit of the water being caught in the second pot

 

essentially if you have your holes in the side of the pot you just have to remember that water will collect in that area and then drain when it overflows , so an air stone down there isn't a bad idea at all , it also introduces extra air to the roots which is never a horrible thing

 

 

Hope that helps

[Indycar]

I dunno if it necessary for ya to purchase hole saws. But if you only plan on going thru wood, plastic, fibro, panel board, MDF board, etc... You could possibly consider these tools. For the smaller holes for plumbing etc. I use the wooden spade bits. For 13mm (1/2 inch) holes for grommets, use the 16mm bit, and for the 19mm (3/4 inch) holes for grommets, use the 22mm bit.

 

As for cutting larger holes, I go the adjustable hole cutter. The one i got is only good for holes up to 140mm, i really should've got the next one up. Anyway, why i thought i'd mention this is because of possibly being a cheaper option. I think i paid like $4 for the spade bit set and $12 for the hole cutter. For under $20 at Bunnings, it seemed to be the cheaper option for me. Fair enough these are cheap quality tools, but if you've seen what projects i've used em on. You'd see i got me monies worth, several times over.

 

[SukonmiSkunk]

yes.. the 13mm tophat gromets. will use a 16.. or 17 mm drill bit.. i got a 16mm holesaw bit.. works perfect....

[RobbieGanjaSeed]

Thanks indycar, I've used those at a pinch, but more than once I've seen a wrongen shaped hole and a real stuff up. I once actually got a guy who runs (I wont say what hydro shop, anyone can make an error and doesn't need bad mouthing I suppose). I built a " beaut" system, and it all depended on one water tight fit at the bottom and away it went. It was an aero system and the bottom tank cost a fair bit, maybe 80 bux. I paid this bloke to put the last few fittings on, because I didn;t have a hole saw, and figured he would do a better job, he used a splade drill and mongreled the hole, just a slight oval shape, you could hardly see it. but it wouldn't seal and man it drov me nuts. In the end I drilled it out, and placed a screw type bung in it, and re-drilled it myself with a borrorowed hole saw.

maybe you have steadier hands than me is all mate.

 

Pure, thanks for that. the air stone idea was exactly what I was thinking. I was tossing up if I should actually combat the potential build up of "stale" nutes by intentionally placing the return hose a few inches high, and placing in an airstone, and there-by not only protecting it against a buggered nute pump danger, but to capitalise also on a combination of the dripper effect and a bubbler.

 

What do you think of actually doing it that way? I mean making it say3 or 4 inch deep on purpose?

 

 

 

thanks all.

 

rob

[Pure]

What do you think of actually doing it that way? I mean making it say3 or 4 inch deep on purpose?

thanks all.

 

rob

 

 

I think that although that much isn't "needed" you could get away with it , the only thing that I would suggest is to have at least an inch space between the top pot and the water level and an airstone is a definite requirement

[Tom]

High Robbie, what sort of grow media are you using? Both perlite and coco weigh very little when dry so they would be easier on your back than soil or clay balls.

 

[RobbieGanjaSeed]

Hey Tom, clay balls I'd reckon. I've always used them, and the mere thought of anything else makes me shudder. I'm not one for change .

 

Serious though, it would be expanded clay for sure. I see what you're saying about Perlite, but I've only grown directly into straight perlite a couple times and it felt "odd" each time. I wonder if the clay balls gives me some kind of subconscience things with the earthy colours?

 

cheers all. thanks heaps too.

 

rob