What size pump is the best for me? - Check my math

S

SALT

Premium Member
[Hello All,

I am in the process of getting all the parts and pieces for my new 105 set up and I have a check my sanity question. I think a Mag 9.5 is the return pump I want to use. The tank has a single overflow with a 1 inch drain. I went to RC and used the Head Loss and Drain/Overflow Size calculators and this is what I came up with.

I played around with the Overflow calculator to determine what the maximum amount of flow that could go through the 1 inch return and determined that it is 592 gallons per hour.

Then figured the head loss. My tank rim is 60 inches or 5 ft tall. I figured in a few elbows, a union and a ball valve all at 3/4 inches due to the return line bulk head being 3/4 inches and of course the Mag 9.5 and it said,

"Total losses are 6.52 feet of head pressure, or 2.82 PSI. with a flow rate of 677 GPH"

Now 677 - 592 = 85.

Assuming the calculation are correct that means I would be pumping in 85 gallons more an hour then the drain can handle. That would run the sump/refugium dry and over flow the tank, right? I also assume I could add a T and a ball or gate valve in the return line and use this to regulate some of the flow back to the sump.

Does this all make sense or do you thing a Mag 9.5 is too much pump for a single 1 inch overflow?]
 
[Sounds perfect. You would much rather have to much then to little. You can always divert more back to the return section of the sump if you need to.

You also should realize that if you use a durso or stockman that will cut down some more so you may get a little less (due to that linear length suggested basically being zero) then you think. Maybe 400-500 GPH. Still perfectly acceptable. I think you could get away with a Mag 7 but for $15 more go with the 9.5. It also has 3/4" inputs and outputs for easier plumbing!]



Edited By kwl1763 on 1103234970
 
[I have an Oceanic 90 and I believe the drain is the same size as yours. I'm using a Mag 9.5 and it works fine.

I set it up with a "T" on the return so I could reduce the return rate if I wanted to and redirect some back into the sump area, but I have it about 90% open right now Works great.

The only problem I ran into was it took a while to get the return setup just right so that I wasn't blasting the sand everywhere. A Mag 9.5 running full tilt generates a pretty strong water stream.]
 
[You guys are lucky. My mag 12 is IMO too weak. I do however have it plumbed through my chiller. I assume I might get 700 GPH out of it. :cussing:]
 
[granted, I only have the lights on for a couple of hours a day b/c I'm still cycling the tank, but with the MH's 11" off the water and fans blowing in the canopy and in the sump - my tank stays at exactly 78 degrees w/o a chiller.

I actually had to turn off the fans in the sump when the temp dropped back down a few days ago (I keep the house heat set at 71 in the winter) because the heater couldn't keep up.

I figure I can run at 80 next summer with no problem...]
 
[Hey Keith,

I am going to use the Stockman mod on the overflow, will it really decrease the flow rate that much?

Hey Chirs,

My original plan was for a 90 but when the 105 came available I went for it. Yea they probably do have the same set up for drainlines so I guess the Mag 9.5 is gonna be OK. Do you have a stockman mod?

Hey Mitch,

I was originally going to go with a Mag 12 until I did some calcuation. I think the Mag 12 would be way to much for a single overflow.



Trust me Louie, it has been a long time comming. I have been getting bits and pieces now for over a year. I just got the cabinet built last weekend and I am working on getting it finished. As you can see I am still working out some of the details, but you can be sure I will be putting up a post soon asking for some help with the move some time between Christmas and New Years. I am very psyched up about it. :lol:]



Edited By SALT on 1103236504
 
[Yes, the Mag 9.5 will work well in this application. This is how I redirected the water back into the sump when my 55g was set up.

return.jpg
alt="">]
 
[I did mine just like Marc and yes it will decrease the flow quite noticeably! I have never yet seen any real calculations but when people have added them they have seen fairly drastic reductions.

Again on Mitch's comment. Your return pump should not be your main method of circulation. Only 3 to 5x through your sump is great! Add closed loops and/or powerheads to create the in tank turnover.]
 
You must log in or register to reply here.
Top