Max Flow - Max Head ??

[AmherstReef]

So when I bought my BlowHole 1450, ReeFlo clearly charted out GPH vs Head Height.

1450 gph at 0'
1221 gph at 6'
994 gph at 13'

Which is exactly what I have, 13'

Now I'm looking online at new pumps and all they say is Max Flow and Max Head.

Do they mean the Max Flow is at 0' or is that the Max Flow at the Max Head for that pump ??

 

[mr.maroonsalty]

I would take the two seperately, but do you have an example?

 

[blanden.adam]

Max flow is the flow at 0' head, max head is the point at which the head pressure becomes sufficient to reduce the flow to 0 gph. Separate things trying to get at the "power" of the pump, but like you have pointed out, neither are particularly useful. The full chart is what we really need to see if a pump will fit our application. Manufacturers will usually have it in their technical documentation for the pump somewhere on their website.

 

[AmherstReef]

Thanks Adam, that's kind of what I thought. So if I need around 1000gph at 13' I'll need to figure out which pump will give me that based in its max flow

 

[leveldrummer]

Thanks Adam, that's kind of what I thought. So if I need around 1000gph at 13' I'll need to figure out which pump will give me that based in its max flow

ignore the max flow and max head numbers, find a chart that shows how much flow you will get at specific heights.

 

[SkiFletch]

Yeah, max head and max flow numbers are useless to you if you're thinking about a different pump. What you need is either the pump curve, or the table used to generate the curve. It lists what all the resulting flowrates are at various head pressured. For the Blowhole, I found

Keep in mind, if you have 13' of vertical head, you need to add some pressure drop for fittings and stuff too, so you're probably closer to 14 or 15' of actual head. Luckily for you, the blowhole pumps look like high-head pumps so you're talking 900gph or so.

Why do you want 1000gph? That seems like a lot of flow through a sump for a 90g... I'd be comfortable with 500-700gph on a tank that size, so you've got plenty of flow through it with the blowhole.

 

[AmherstReef]

I had the BlowHole 1450 before it seized up and running it on high gave me the right amount of flow. I was estimating 13' head pressure, 10 vertical, 3 horizontal, two 90's and one ball valve . So using the BlowHole chart I estimated my flow at roughly 994gph.

 

[mr.maroonsalty]

Reeflo explains friction losses well here; I'm sure there is sooo much more as this is an entire field of engineering study:
http://www.reeflopumps.com/images/tips.pdf

Total head isn't just about measuring height and adding up fittings; pipe diameter is critical. There are equivalent lengths for each size fitting that can be found and simply added to the total length of pipe, then you turn that length into a percentage ie. 10' 1 1/2" two 90el (I believe they are 3' each) becomes .16 x friction loss per 100' for the specific flow rate. I went with reeflow because of there reliability, service, and low watts; I hope it was a good choice.

 

[SkiFletch]

RC calculator will do this for you. At 1" pipe, the system you describe has 10.52 feet of head loss. With 1.5" pipe, it's 10.1 feet of head loss, and with 2" it's 10.03 feet. Not 13 like you're thinking. You're right that the pump's gonna push around 1000gph. This is also better news for your magdrive temporary, as it can still function enough at 10 feet

 

[AmherstReef]

I looked at that but it changes head loss depending on the pump and I don't even know what pump to plug in .

 

[mr.maroonsalty]

RC calculator will do this for you. At 1" pipe, the system you describe has 10.52 feet of head loss. With 1.5" pipe, it's 10.1 feet of head loss, and with 2" it's 10.03 feet. Not 13 like you're thinking. You're right that the pump's gonna push around 1000gph. This is also better news for your magdrive temporary, as it can still function enough at 10 feet

Which pump did you choose in this calculator; it doesn't have reeflo pumps?

Here's my math: .10 (10' -> 100') + .045 (4.5-> 100' equivelent length 2 1" 90el) = .145 x 32.88 ( friction loss per 100' 1" PVC @ 1500 gph) = 4.78' + 10' gravity = 14.78' head loss.

 

[mr.maroonsalty]

If you use the iwaki 70 rt, a 1500 gph pump you'll get 14' with 10 vert and 2 90 el. If you simply use 10' horz run and two elbows you get 6' of head; I don't know what it is doing with the 10' of gravity when it loses 2' head from the calculations? The extra loss from my calc is likely because it uses the eq. Length for a sharp turn 90 el which is 5.3 feet eq length per hundred

 

[AmherstReef]

That's what I got too, I may just get a second BlowHole 1450, whatever flow I'm getting with it, it's perfect

 

[SkiFletch]

I used a mag 9 to generate since he's using it for backup.