Good video! I really enjoy this series.
So I'm a self professed nerd and also a mechanical engineer who can crunch the theoretical numbers on this. I had a calculator I made for sizing a basement return pump and I plugged this setup into it. The theoretical loss difference between the two options tested at 950 gph is only 0.12 feet (and the calculations aren't that accurate anyway, only within 10% at best). Theoretically two 45 are worse than a single 90, and there's 3 extra joints which also have a small loss associated with them. A long radius (1.5 x D) 90 degree turn is better than both options tested (by almost a half a foot), but hard to find in schedule 40 or 80. If only there was someone around here who could source long radius 90's in schedule 40 for a decent price
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The biggest affect to head loss by far is pipe diameter, and there is absolutely nothing wrong with upsizing the return line. So if your pump outlet is 1" you can run a short length of 1" pipe and then upsize it to 1.5" for the rest of the return for "free" extra flow! This is a big deal for basement sumps and long return lines. Not such a big deal for 5' runs from directly under the tank. For reference, my future basement sump return line head loss drops from 15 ft to 12.5 ft if I upsize the return line from the pump outlet of 1.5" to 2". This is an extra 300 gallons an hour of flow for free in my case. People also need to make sure they aren't downsizing the returns through the bulkhead and locline into the tank (if they get a choice). Even just a 1' run of locline that's to small of a diameter can cause a huge reduction in flow.
If you guys have any questions ask away!
I was honestly surprised myself, especially from all of the advice about 45s vs 90s I read about as a beginner. That sort of "rule of thumb" has stuck with me ever since.
I wish we could have extended this into other fittings also. I'd be interested in the impacts from Tees, reducers and bulkheads.
What are your thoughts about fittings and their effects on drain lines?
-Randy
Just make sure your drain line is over sized a little and it really doesn't matter. With return lines you're paying extra for loss by losing flow or having to buy a bigger pump so it's worth it to do a little optimization. With drain lines there's no consequence based on your fittings unless you undersize it. The chart on this page is a good reference for drain line sizing
http://www.reefaquarium.com/2012/aquarium-plumbing-basics/
Good to see lack of difference proven but for me this raised the question that is common to most of our systems. splitting output from a pump to two or more outlets, what is the impact of where/how this is done on GPH?
It's small. As
@McArcher mentions, don't use tee's with a reduction on both outputs (one of the outlets can be reduced if you purposefully want lower flow in that branch). Also, you should have the branch where you want the most flow to go to be the straight through branch (which is kind of obvious I think). If the flow going into the T is 500 gph, the flow coming out the two sizes added together will be pretty close to 500gph.
I've always wondered what's really the optimal return flow "turnover" rate. Is is 10x tank volume, 5x, 2x? As you increase from 2x and higher there's a huge cost associated with the increased flow in both a larger pump being required, and more electricity to run the pump. Testing on this would be really interesting to me. Start on an established tank that's doing well and reduce the turnover 1 month at a time or so until there's a noticeable negative effect (who's going to volunteer to potentially trash their tank though
). I would guess the optimal flow rate would be the lowest rate that keeps the sump and tank homogeneous (the same). You could measure differences between the sump and tank, with the target of keeping the two relatively close (temp, dissolved oxygen, nitrate & phosphate, ph, dkh, etc.). But maybe that's not necessary and even lower turnover rates than that could be ok if you keep the display tank in the "target zones" (so up the temperature in the sump so display tank is at it's target temp).
