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Any recommendations for an alternative to uniseals?

Discussion in 'Hydroponics / Aeroponics' started by dusty8940, Jan 3, 2013.


    dusty8940 Member

    I am working on building myself a recirculating deep water culture system, similar to that of current culture. I have built a couple of these for friends and found that the uni seals used on these are a huge pain. So I found a better alternative for this using shower drains. These work well because they have a screen in them that can prevent the roots from clogging the system. However, you have to glue these to the adjoining plumbing pipes and I would like to make this portable incase I move. So I am wondering if anyone has any ideas as to what could be used in place of uni seals? I am not too familiar with all of the different plumbing fitting, but I have to assume that their is some other type of compression fittings or something that could work, yet be easy to disassemble in the event of me moving. Also, a link and or picture would be very helpful. Thanks in advance.

    Murfy Well-Known Member



    dusty8940 Member

    THanks for the fast reply. Pleaase forgive me for my lack of knowledge with plumbing fittings, but can you tell me how these work? Do you just shove the thinner end into the holes in the buckets? Does this provide a water tight seal? Thanks

    tallen Active Member

    Each end slips over a pipe of the appropriate size, I don't see how they could be used in place of uniseals myself. Maybe Murfy will pop back in and explain it for us. Maybe glue a short piece of pipe on and then use a flexible coupling like that?

    haole420 Active Member

    to answer your question, no, i don't no of anything better than uniseals to get a watertight seal on a round/curved plastic surface. i love uniseals. they do the impossible, you just have to be very, very precise when drilling your hole (less than 1/8" off).

    uniseals can be a bitch if you drill the hole too big or not smoothly enough. i've got a graveyard of bins and garbage cans and buckets i messed up. they do expand when you plug a pipe in them, but not a lot. and they won't fill in chips and large irregularities. the hole has to be smooth. that's key. high speed seems to melt the plastic smoothly after cutting it. practice on the lid if it's the same kind of plastic. every kind of plastic is different and reacts differently to different bits, speeds, torque settings, etc.

    i like using a step bit for smaller holes (1-1/4" for 1/2" and 3/4" uniseals), but it's easy to go too far and make the hole too big. make your mark and start on the outside. about halfway through, drill from the inside. drilling it from both sides gives it a burr-free cut. i find that i get a more precise cut when i finish the hole from the inside. having a helper support the plastic so it doesn't flex when you drill it will also give you a more exact hole.

    for bigger holes, i use a hole saw with pilot bit. after you pierce the surface with the pilot bit, make sure the cup saw is spinning at a pretty good speed before making contact with the surface to be cut. if it's not spinning fast enough, the cutting edge can snag, and torque the entire drill in an unbalanced, off-axis, dangerous way that gives you an uneven hole that will leak. i like to drill the pilot hole with a plain 1/4" drill bit from the outside, then actually cut the hole from the inside out. obviously, you won't be able to do this with a 5-gallon bucket.

    with both methods of cutting holes, precision is the key. not just a consistent diameter, the edge of the hole needs to be perfectly smooth.

    if you have to manually deburr, use your fingernail or credit card. don't use a knife.

    the second problem people run into with uniseals is difficulty in getting the pipe into the hole.

    to get the pipe in the hole, lube it up with plumber's silicon grease. best stuff ever. i use it on both sides of the gasket for bulkheads too. the lubrication lets you really turn the nut with a lot less friction from the rubber gasket. another thing you can do is to slightly taper the edge of the cut pipe. i've seen tools to do this at the hardware store. i've used a utility knife with success to manually cut a 45-degree bevel in the outside of the pipe. doesn't have to be perfect, just enough to get it going, but i don't even do this anymore. just lube up the inside of the uniseal good and plenty and ram it in there. if you get the lube on a surface you're going to glue, use a clean paper towel to wipe off any excess and be sure to use a purple primer before gluing.

    if you're not using a ratcheting pvc cutter, then spend the $10 and get one. it gives you easy, perfect cuts. i have one small one and one that can handle up to 2" drain pipes. you can also use a chop saw, but i find the hand cutter easier and faster to work with. pipes cut with hacksaws give you a rough edge that won't insert smoothly. chop saws can chip and melt the pipe, potentially making it more difficult to insert. the ratcheting hand cutters are really the way to go.

    hope that helps and you have better experiences with uniseals! if you do find of another product, please update this thread!

    panhead Well-Known Member

    Fernco fittings are a plumbing industry standard & are used in many critical plumbing applications.They are your best choice if easy disassembly is what your after.

    They will not leak or fall off once tightened as long as they arent over torqued ,fernco sells a small torque wrench made special for the 5/16 tightening nut for about $15.

    panhead Well-Known Member

    Fernco fittings are a plumbing industry standard & are used in many critical plumbing applications.They are your best choice if easy disassembly is what your after.

    They will not leak or fall off once tightened as long as they arent over torqued ,fernco sells a small torque wrench made special for the 5/16 tightening nut for about $15.

    bazookajoe Well-Known Member

    that's a coupler for 2 dif size pipes.. not a water-tight seal for a bucket hole 0_o

    Murfy Well-Known Member


    i thought you were using tub drains. continue to do so. the tub, sink, uniseal fittings are all variations of what are known as bulkhead fittings. these are fittings that are used to put a hole through (a bulkhead), sealing, and providing a nipple.

    blow up pools have them. scavage the ones you see on the side of the road. any plumbing ssupply house will have a plethora of the to choose from. including rounds of varying size.

    after your bulkhead fitting is in place, instead of a cemented joint, use the fernco to adapt to your plumbing. they come in many configurations.
    hope that helps.

    haole420 Active Member

    uniseals differ in the fact that (1) they aren't rigid and (2) they are designed to allow a pipe to pass through a curved surface. the last time i changed a tub drain, the flange was curved to accommodate what i assume is an industry standard curve in the tub drain and sealed with plumbers putty on the inside of the tub. a gasket seals the drain from the outside. bulkheads are also rigid and pretty much the same design as the tub drain except the flange is flat.

    bulkheads and tub drains won't work in a curved surface. they're designed to work with flat surfaces. the smaller the radius (tighter the curve), the more bulkheads will leak. with a thick/elastic enough gasket, you might be able to overcome the gap, but then you're putting uneven stress on the flange, which is made of hard, breakable ABS plastic. i've never been able to get any bulkhead to give a 100% leak-proof seal on a 5-gallon bucket or 55-gallon garbage can. uniseals will do the trick as long as your hole is within fairly tight tolerances and smooth.

    the ideal solution would be a rigid bulkhead fitting with two curved flanges to match the curvature of a 5-gallon bucket (or other application), one for inside and one for the outside. the outside nut and flange should be separate. both flanges would not rotate since the pressure from the nut and curvature of the bucket/flanges will lock the flanges into position.

    haole420 Active Member

    is this what you're talking about?

    those are pretty much the same thing as uniseals with the addition of the metal clamp. you can add such a clamp onto a uniseal provided the wall your going through isn't super thick. i'm pretty sure the clamp is only to secure the pipe, not to provide a watertight seal.

    the only problem? they come in 4", 6", and 8". uniseals start at 1/2" and go up from there.

    ilikecheetoes Well-Known Member

    I take these things http://www.ebay.com/itm/Fill-Drain-...ad-1-2-Flo-System-Tray-Bulk-PVC-/120839495815
    the side that has the net on it actually just pull right out. Then I glue a 1/2" PVC pipe about 2" long where the net used to be. Then I have a hose side and a PVC side on either side of the bucket.. Obviously Im using it to attach to a pump in the rez and not a recirculating system so I doubt a 1/2 pvc is big enough. You may want to get one of the 1" ebb/flow drains.

    oh yea and fuck uniseals. they are the biggest piles of shit ever. leaking mess unless you gum them up with silicon which defeats the whole point.

    ilikecheetoes Well-Known Member

    oh crap i just remembered what I did with my RDWC.
    I used these http://www.grainger.com/Grainger/CANTEX-Female-Adapter-4FYA5 and the male on the other side. I got some grommets ( not grommets, rubber washers) at home depot that fit them perfectly. then you have a 2" pvc on either side. thats big enough for any rdwc. Been a couple years and it just popped into my head.
    I've come up with all kinds of home depot bulk head rigs to avoid uniseals at all costs.

    haole420 Active Member

    and you got a standard bulkhead to seal against a curved surface like a 5-gallon bucket? i think that's why the OP was asking about uniseals in the first place. they're not replacements for bulkheads, they're for a completely different application.

    i've only had to silicone up one uniseal because i didn't drill the hole smoothly. smooth hole, no leak. i'm probably batting 49 for 50 or so. not one leak, not one bead of silicone (except for the one fuck up)

    by the way, we're not talking about standard grommets you pick up at the hydro stores. those ARE shit. uniseals are a little harder to find, only have a flange on one side, and require a hole significantly bigger than the pipe diameter. 1-1/4" hole required for 1/2" and 3/4" PVC. so if you don't ever remember drilling a 1-1/4" hole, then you probably haven't used a uniseal before.

    haole420 Active Member

    i still don't get how this DIY rig with threaded adapters solves the problem of the curved surface. yes, this is a known technique for flat surfaces in the absence of a bulkhead, but bulkheads do NOT work on curved surfaces, period. teeny tiny (albeit, perfectly fitting) washers or o-rings aren't going be able to seal up a hole in the side of a 5-gallon bucket with a 1/2" MPT and FPT adapter. i'd like to see something like that at the bottom of a garbage can filled with water. i have two 1/2" uniseals that i just installed that are under the pressure of about 2ft of water in garbage cans. not one drop. try that with two threaded PVC adapters on the curved side wall of any round garbage can, and near the bottom where it's under constant pressure.

    uniseals work great if you know how to drill a smooth hole within the designated tolerances.

    ilikecheetoes Well-Known Member

    the curved surfaced never mattered to me because im not trying to seal metal or hard plastic buckets. If you tighten it down it flattens the plastic and creates a seal. Its only a 2 inch hole so it doesnt have any trouble pulling a rubbermaid or 5 gallon bucket plastic flat. that shit is thin and flexible plastic.
    I use a brass hole cutter and I have an edge scraping deburring tool as well. My holes are smooth as my wifes hairless ass.

    haole420 Active Member

    sorry, cheetos, but i call b.s.

    I've tried bulkheads on 5-gallon buckets from hydrofarm, home depot, and lowes. you might be able to flatten the bucket somewhat, but you'll never get a seal with a bulkhead, especially at the bottom of the wall where the bottom of the bucket will prevent you from flattening the bucket (and where you usually want the drain). even the top of wall will be tough with the lid locked in place.

    in order to get THAT much pressure to flatten the bucket to the point where the grommet will be compressed and for a seal, the torque is likely to strip the nut or threads of the cheap plastic bulkhead or break the flange before you ever get it to stop dripping. i know because i've had all three of these things happen.

    better yet, try that in a 20-, 32-, or 55-gallon rubbermaid "brute" garbage can, again, near the bottom. with 2-3ft of water head, your garbage can will have completely drained itself through the leak with a bulkhead within an hour, if not minutes.

    again, these aren't grommets for barbs and vinyl tubing. uniseals are designed for used with rigid pipe.

    here's one of the 20-gallon garbage cans that tops off my flood/drain res. that's 1/2" sched40 PVC, btw. notice the can is almost full of water and there isn't any sign of leaking on the can or floor. no way in hell you can pull that off with a bulkhead.

    2013-01-16_11-21-11_177.jpg 2013-01-16_11-21-51_743.jpg

    another bonus: the pipe slides through the seal uncut. here are pics of a 3/4" drain on a flood tray. it's a flat surface that i could've used a bulkhead on, but with a uniseal i can adjust the water level by just sliding the 3/4" PVC up and down through the seal with a little plumber's silicone lube. with a bulkhead, water level is fixed or requires a bit more complexity to adjust.

    2013-01-16_11-23-03_256.jpg 2013-01-16_11-23-14_708.jpg

    here's an extreme example of what you can do with them, pulled off the web. the tighter the radius, the more impossible it's going to be to seal with a bulkhead. again, no way in hell this would be possible with bulkheads. just goes to illustrate that bulkheads are not designed for nor will they seal ANY curved surface, regardless of how tight the radius is. uniseals do work on ANY curved surface and they also work just as well on flat surfaces.


    uniseals' low profile is also a bonus. the male threaded part of the bulkhead that you screw the nut onto is going to stick out, either on the inside or outside. for smaller pipe diameter, it isn't a big issue, but a 1-1/2" bulkhead does require about 2-1/2" of clearance. the 1/2", 3/4", and 1-1/2" bulkheads are all about 1/2" thick.

    i doubt i'll convince cheetos, but anyone else wondering how to seal a hole in the side of a bucket, here you go. a bunch of reasons to use uniseals.

    ilikecheetoes Well-Known Member

    blah blah blah wall of text. I dont give 2 shits what you call bs on. Why would I waste my time making shit up on an internet forum. He asked for ideas. I gave him what Ive done in the past.


    corytrevor2014 Member


    waterdawg Well-Known Member

    Get square pails! Actually unseals work very well when i have used them. I actually use a small torch to clean up the holes, but thats probably not necessary.

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