Backyard Aquaponics
A place to discuss aquaponics

What size bulkhead do I need for 2" pipe/ couplers? The coupler/connector I want to use is a Holman dwvf0242 male iron connector. This will screw into the bulkhead and then the standpipe will slip into the other end.

Is it the 2" bulkhead?

The Internet is being very unhelpful!

Thanks in advance!

for bulkhead fittings to the fitting you describe usually have to get a female-female threaded fitting to go between.

is this for the fish tank or grow bed ?
2" bulkheads would be getting pretty expensive.
Bulkheads OK (good idea) for sump but may not be necessary for lower pressure situations in GB or SLO. In these cases there are other options.


Also you can cheat and go female threaded direct to PVC for a lot of things.
So something like a PVC threaded faucet socket would work - http://www.holmanindustries.com.au/prod ... et-socket/ Basically the female opposite of the male connection you have and about same cost.

*But* if it is higher pressure you should really go nylon bulkhead to nylon screw fitting first and then to PVC with plumbers tape (relates to materials expansion).

[edit] also be very careful. You show DWV fitting and therefore are potentially mixing sewer/drainage and irrigation fittings and the two do not match. Same with the pipe. Different standards. You should try and stay with white irrigation PVC not grey.

I was wanting the bulkheads for our Growbeds.

Is this not the right kind of bulkhead?

$6 seems pretty affordable to me

yep those are fine. Wondered if you were talking about similar ones to the sump.
(although 2" sounds large for GB standpipes)

in which case you should be able to get a threaded faucet to fit.
(see previous post). They too will only be a few dollars.

p.s. what's the site you show. I got some cheap Chinese ones via eBay at one point and they did not snug fit to the standard pipe sizes. (in that case plumbers tape did the trick).

The website is aussieglobe.com

I thought it was an Aussie website but shipping is from the states.

Shipping costs $25

So that takes the price of each individual bulkhead up to $11 each

But it's still the cheapest option

2" sounds large for GB standpipes, what specific bit of the GB are you getting it for ?

[edit] uniseals may be even cheaper. Can you combine shipping ?
Worth grabbing a few at $1-$3 anyway if already paying for postage.

Brain not working too well today...

Is 50mm ok for a standpipe and plumbing to drain the Growbeds?

Somehow I had the impression that the faster your grow beds drain the better. The SLO from our fish tanks will also be 50mm but Each growbed outlet will have a ball valve.

It would depend on method you are going to use and what the respective threads suggest.
Ultimately it comes down to flow rate but I would have thought 50mm is large.


For a multiple-IBC growbed system many use 25mm (eg. IBC aquaponics*) and some use 32mm. [Maybe 40mm]
This would be similar/same for Constant Flood. Then you usually have a 90mm surround but that is not attached.
(only the 25mm or 32mm goes through).

[eg. For siphons search for one of Mr Damages siphon comments, he specs them out with pictures. ]

* I know the IBC-AP shows the 50mm adapter but that is only needed to fit the IBC screw cap fitting.
They then have to use a reducer to drop size down and finish up with actual standpipe of 25mm.

A through pipe for siphon etc for instance would just use a 1" or so uniseal.
In moulded GB's usually use a 25mm or 32mm screw fitting.

may need to check back with whom-ever's system you are working off.

however I would suspect based upon you other posts that your flow rate is around 3000L/hr.
Your 50mm SLO/s is going to feed out to a single 50mm pipe all the way back to GB's.
(maybe via a filter). So at most your flow rate is basically in one 50mm pipe ?

You will have at least 2 GB's, probably more to get the 0.6-1/1 ratio.
So unlikely you would need 50mm standpipe.

*but check* - because I could be mis-understanding your planned system.

even if a 50mm standpipe isnt "needed", you cant go wrong with having a drain too big, but you can certainly have them too small....

Part of the problem I'm facing though is once you go up to 50mm, especially constructing a bell siphon for 4 Growbeds 50cm deep, the materials and fittings become harder to find and more expensive.

Can I do a 40mm standpipe?

Nah - the shipping keeps increasing. Changed my order to 10 bulkheads just to test and sipping went up to $42!

3000l flow, between 4 beds?

chances are yes, 40mm will be ok.

check some of Mr Damages posts. He gives you the ratios and he tends to stay with KISS.
issue with siphons is they are inherently linked to flow rate.

eg. use the search near the "new messages" and "members" menu above.
use 'Search for Author' box - enter 'Mr Damage' and then 'siphon'

it will give you quite a bit of information.

correct sizing of the siphon pipes, bell and fittings is pretty important.


Sizing much less issue for a constant flood or timer style system.
(just has to be big enough for max. flow)


[edit] a search on 'siphon standpipe size' also returns some useful things to consider.

re: 40mm - may be a bit large for IBC sized GB's. But it comes back to flow rates.

I've mixed 50, 65 and 100mm DVW (grey) pipe with 25 & 40mm pressure and 90mm SLO in several places using uniseals, sockets, faucets, slip joins and black threaded irrigation fittings. Some are tapered, others require teflon tape or glue but they all work together well with no leaks, just don't use non-pressure pipe or fittings on a pressurised line.

Perhaps work out your pipe sizes and we can advise on how to adapt/combine them.