Flow Rate help: first tank

gridley · #1 05-26-2012, 09:45 PM

Thank you very much -this is a huge help.

gridley · #2 05-27-2012, 10:18 PM

Hello Myka - As it is a slower day I just reread your reply and I wanted to say that I really appreciated your reply and the information that you have included. This has been a help as I try to figure out what steps to take.

My return line is plumbed through a bulkhead in the side of the tank and until I take things apart I do not know if there is room for a 1 inch buldhead to be put in the hole. One question that I still have relates to the lok-line that is attached to the return line. The lok-line I have has a 3/4 inch fitting - if I increase the pipe diameter to 1", and keep the current 3/4" lok-line fitting, am I gaining anything? I was looking at seveal sights for a 1" lok-line fitting and did not find any. Is there such a size? Are there other options?

Thanks

Myka · #3 05-27-2012, 10:47 PM

You're welcome.

It is unlikely that you could fit a 1" bulkhead in a hole that is drilled for a 3/4" bulkhead unless some weird size was drilled. That is just really unlikely. Since the tank is already drilled with a 3/4" bulkhead installed you may as well use it. One thing you can do is make sure that thin-walled PVC was used rather than thick-walled (SCH40) PVC. Using thin-walled PVC will give you a slightly larger internal diameter of the pipe and therefore allow a slightly higher flow. Just take the pipe size into account when figuring out head loss. I wouldn't change the 3/4" loc-line. You won't find 1" loc-line because it is not made.

sphelps · #4 05-28-2012, 12:25 AM

The 3/4"bulkhead won't make a difference. The head loss resulting from smaller pipe is from friction alone so that 50gph loss you're seeing is purely from the extra friction from the length of all the pipe and fittings. Increasing the pipe and fittings to 1"will still give you the same gain despite the bulkhead at the end staying at 3/4", this will only act as a nozzle increasing velocity but flow rate for the most part will be unaffected. I should add I agree the pump is a bit small, personally I like to run larger return flow rates to cut back on the need for supplemental from powerheads.

Myka · #5 05-28-2012, 12:49 AM

What Steve says is true, but I wouldn't bother changing the size of the pipe. It's already there, may as well use it. Unless it is plumbed weird. If it makes the difference between on size pump and the next size up then I would definitely change it.

gridley · #6 05-28-2012, 01:35 AM

Well, latest inteligence shows (while testing the plumbing) that I should not become a plumber. I have one joint leaking in that line . . . so, I quess that I will increase it to a 1" line and maintain the 3/4" bulkhead, which if I understand what is being said, will not signifianctly decrease the flow, but only increase the velocity. So, I will now get my brother in law plumber over to do it correctly.

Thanks to everyone for the help and advice on this seemingly never ending challenge of getting water into the tank.