View Full Version : hole size for 108 gallon bulkheads

09/18/2017, 03:25 PM
Im having a 108 gallon acrylic tank built. I'm making sure that I ordered it correctly. I asked for 3 of 1" drain holes, 2 as the main and 1 as an emergency. I'm thinking that I won't need more than 800 gph getting to the tank after head pressure, friction is considered. Might even go with a 1000 gph rated at 0 ft. I currently have Tunze 3 that will run on it, and can soon get another 1-2 tunze (smaller) to add to this flow. On a tunze wave controller.

**The return is only 3/4". Should have I have two returns coming in on separate 3/4" tank drilled holes? Will 3/4" accommodate up to 800 gph?

**tank is about to start build, so I need input asap :)


09/18/2017, 03:32 PM
I would always go to 1 1/2" for an open channel/emergency; 1" is fine for any drains that will be siphons. A 3/4" return can push 800 gallons if your pump is up to the task

09/18/2017, 03:37 PM
5 x 1" schedule 40 bulkhead holes IMO...
1" is plenty for bean on a 100G

use 2 of them for returns.. 1 is fine but I always like 2 return outlets..
No harm in oversizing the return outlets..

09/18/2017, 04:36 PM
5 x 1".. is that 3 of drain and 2 return?.. will be mainly sps .. most of the flow would be coming from my wave maker pumps.. thanks!

09/18/2017, 05:07 PM
yes.. 5 x 1" bulkheads.. 3 drain (bean system) and 2 returns

09/18/2017, 05:50 PM
what if my out put to my pump is a 3/4 barb? still use the 1" bulk heads for the return? I will likely upgrade soon. can a 3/4 adapt to the 1"? thanks

09/18/2017, 06:45 PM
bump.. only b/c tank is in process of being made. **So, a pump with a 3/4" out put barb can adapt to a 1" bulk head?
** That 3/4" barb pump is what i have now. I think it is 750 gph only. I will likely go higher as I said previously. But if I need to get a higher pump now to push though 1" then I will... but I'd rather not right away, as I have a lot of expenses. So I'd prefer my current pump with 3/4 barb to be able to adapt to the 1" hole, at least for now.

09/19/2017, 08:01 AM
what if my out put to my pump is a 3/4 barb? still use the 1" bulk heads for the return? I will likely upgrade soon. can a 3/4 adapt to the 1"? thanks

Of course. Use a 3/4 to 1" adapter from your local hardware/plumbing store. Costs about a buck.

09/19/2017, 08:03 AM
yes.. adapters of all sizes are readily available at your local hardware store..

Ask for holes for 5 x 1" schedule 40 bulkheads (which would be 5 x 1.75" diameter holes)... do it... no... do it... do it.. ;)

09/19/2017, 10:50 AM
well, if a pump rated at 750 gph like my current one (at 0 feet), wouldn't the flow be less with a lower flow pump like this using a HIGHER diameter output like a 1" as opposed to a 3/4"? I was thinking this could be true due to it being harder for the pump to push the water through a higher diameter as opposed to a smaller diameter (? )
And I thought it would be easier for the water flow to be more turbulent going through a higher diameter and less of a straight flow, because the pressure through a higher diameter wouldn't be high enough due to a low out put pump (of 750 mph at 0'). I would think a highflow pump like 1200 gph would be able to give a less turbulent flow due to it's higher pressure, and therefore a 1" would be for higher out put pumps only.

Let me know if I'm wrong.. as I might be since everyone seems to say 1" hole no matter how much flow I have rated for the return pump.

09/19/2017, 10:53 AM
Also I was thinking to keep a 750 flow pump even for the 108 gallon b/c it would allow the flow through the sump not to go too fast so the skimmer can process the water more efficiently... and I do have high out put tunze stream 3 to use.. and will add to this. So as long as even with this 750 pump, a 1" will allow same flow as a 3/4" then I'll go with the 1" ... 2 of them, and block one off and not use it unless I need to some time down the road.

09/19/2017, 11:12 AM
As long as the pipe is larger than the outlet of the pump you are good to go..
But don't think a 1" pipe is universal for any pump..
It is however plenty of size for a pump that would go on a 100G tank..
Now if you have a pump with a 2" output then having a 1" pipe is a restriction and would hurt the performance of that pump..

And yes there is possibly a point where you can go too big.. But its not gonna happen with the numbers/sizes we are talking about if ever at all..

A 1" pipe on a pump with a 3/4" output is not going to hurt its performance..
I just said 2 x for the return because thats my personal preference and I like it because it splits up the flow.. I would use 1" pipe the whole way and put a "Tee" on it somewhere to split it into each of the 2 bulkheads... A single is fine though but I personally like to always split my returns into 2 (or more) outputs

09/19/2017, 11:52 AM
thank you mcg :) .. I'll go with one, but 1" .. so we'll compromise lol. Thank you for explaining all that. It really helps a lot! ... and to the others that chimed in, all great info. I'm slightly clueless on flow and plumbing, now I have what I need, and my tank is already finished, just needs to put the holes in.

09/19/2017, 02:47 PM
It is unnecessary, in my view, to split the return - especially if you are also using powerheads. All that extra plumbing (and loc line, ptewey) does is add extra friction. While 1" drains are fine for siphons, a 1" open channel emergency will struggle to handle 800 gph. Ok, to get to that point both siphons would have to be completely occluded (which is pretty unlikely), but if one were playing the odds a herbie would be more than enough :lol:. That is why, if I have the opportunity to do a larger emergency, I would.

09/19/2017, 02:56 PM
I think it's going to be a herbie. But I'm already getting on the tank builder's nerves changig the holes. Not happy with his tone actually (I'm in sales, and dealt with very wishywashy customers), I actually only put in one change, and before that said that I might change. So, ca1ore, et al, as of now, unless I call the guy to change, it will be the three drains 1", can be used for anything right now I guess, and the 1" return. The guy that is going to help me plumb it talked about herbie, which I know something about.
So given the holes I' having drilled, will those holes be ok with the herbie (which I think is just 2 holes) + the third back up drain and the 1" return?