View Full Version : Baffle spacing question

02/22/2006, 07:35 PM
I've been reading and reading on the spacing of baffles and wanted to get some opinions on my particular setup.

The sump I'm building is sump is 40x18x16. It will be a shorter but wider version of Melev's Model F sump. The skimmer / drain section on the left will be 12x18. Followed by the baffles to trap bubbles. I would like to do 2" between baffles but I'm afraid that will make my return section in the middle to small. So I was thinking about doing 1.5" spacing.

My return pump is an Iwaki MD70 RLT which is 1500 @ 4' head pressure. I know, I know, why did I get such a strong pump. In hindsight, I would have bought a smaller pump.

The fuge section on the far right will only be 8x18. My only debate is that with the increased width of the sump (18") as opposed to Melev's model F @ 12" I might be ok with 1.5" baffle spacing.

What do you all think? Anyone with a similar situation?

02/22/2006, 11:34 PM
I have the same Iwakii. I ran it out of my basement, and it still gave me 1300+ GPH upstairs. It's for sale now. used it for 2 days while I waited for the new pump to arrive. Any little air bubble and that pump grinds the #[email protected]$% out of it. It could take 1 micro bubble and turn it into 50. I would suggest a closed return loop on a ball valve so you can spinn your wheels and slow your water down. (a bypass) back into the sump.


Roland Jacques
02/23/2006, 01:28 AM
if you are increasing the width by 50% 12" to 18" and only reducing the your baffle distance by 25% your still slowed your flow though your baffles by 25%.

just compare your baffle areas 2" x 12"= 24" or 1.5 x 18 = 27" more area = slower flow = less bubles

02/23/2006, 03:20 AM
The closer baffles on the wider sump will work very well, you will have a slower flow rate through the baffles (per unit of area) as yourfishman pointed out so you should have less of a bubble problem then if you used Melevs sump. Since your pump will be out of the side of the sump you could even do a couple of bubble traps in the return section at the bulkhead to get rid of even more bubbles.

If you need to start out by putting an elbow on the bulkhead that points down into the sump and set it so that it is aprox 1/2 the diameter of the pipe from the bottom of the sump (gets water from the lowest point possible. Then around the elbow build a small box that is picked up from the bottom of the sump around 1/2 to 3/4 of an inch. Place this 4 sided box against the outside of the sump over the elbow. This will cause the water to be drawn from the bottom of the sump at the edge of the box keeping out even more bubbles, just place one small hole in the top of the box so that if any bubbles do build up in the box they can get out when they grow large enough.

This works great if you have enough room around the pump intake and you should, without effecting the amount of water in the return section.


02/23/2006, 06:35 AM
yourfishman and kim,

Thank you for the suggestions!! I never really did the math on the wider baffles, never thought about that. I think that I'll stick with 1.5" spacing and go from there. I can add the box as you said kim. I will have plenty of room for that and not affect evaporation or anything else. Thanks again.

jmkarcz, how did you get the flow numbers or was that a guesstimate? I know this pump is pretty strong, I hooked it up once out by the pool just to see what it would do

02/23/2006, 06:35 AM
Worse comes to worse I can always throttle the pump back a bit with a ball valve. It's a high pressure pump so it shouldn't hurt it right?

02/23/2006, 07:51 AM
Throttling won't hurt it but you'll waste electricity. Actually, you are burning a lot more electricity than you need to. The pump you have uses 345 watts, a more appropriately sized pump is a Blueline NS800 which draws 40 watts. This would still give you about 750 gph which is a little high for a 150 gallon tank (you can get by with as little as 225 gph with the right skimmer). This will save you $100 (sell the Iwaki and buy the Blueline with the proceeds) as well as 305 watts!

305 watts 24/7 comes out to 222.8 kWh / month. FPL charges about $0.10 per kWh after the fuel fees so you will save $22.28 per month in electricity. That is $367 in savings in the first year of operation.

02/23/2006, 08:56 AM
WOW!! I wish I hadn't bought the thing so early. I've had it for almost a year sitting in my closet. I know I can't return it now. Wonder how come it uses so much electricity.

Roland Jacques
02/23/2006, 09:14 AM
chemE i have the same pump a 70xlt in my basement for my upstairs 120 tank. is that actual amp draw or just how its rated amp draw. i never tested the amps draw in going to have to now. more back pressure more amperage right? less back presure less amps draw.

02/23/2006, 09:22 AM
Maybe I'll hook it up and test it first before I get rid of it. I'm not going upstairs or anything. I'll have maybe 6 foot of heigth from the bottom of the stand to the top of tank.

02/23/2006, 03:06 PM
anyone else have any experience with this Iwaki 70?? I appreciate the input!!

Roland Jacques
02/23/2006, 05:43 PM
i just came from my distriutor everyone agrees the amp rating that pumps are rated at is max start up amps.
chem E was going by (list rating) that was max start up rating, when it is runing continuoisly it pulls nowhere near that wattage . i think it more like a 1/5 to 1/2 that depending on the back pressure. but i still want to test it.

$8/mo would jive a lot better with my power bill and i have a fair amount of back pressue, with the tank being 15' above 30' away from the pump and filter
so you can figure maybe around $5 or $6 /month. were the other my be $1 or $2 month

02/23/2006, 05:58 PM
Thanks a lot yourfishman... I thought that seemed a tad high but then again I have no idea. I'm going to go with the 1.5" spacing and let it fly. I'll be gluing the second and third baffles tonight. Once the sump is finished, it's time to drill the display (shaking in my boots).... :)

02/23/2006, 06:37 PM
I haven't been able to find a power curve for these pumps so I can't say how many watts it is drawing at your proposed head. Either way it would appear to be a hog (sorry). 1/5th of 345 (69 watts) is still hefty compared to the Blueline (40 watts max). If it is something you choose to afford no problem, I just want to make you aware. I've seen a lot of people here on RC complain mightily about their tank bills.

GoldStripe - Height from the bottom of your stand doens't matter. You need to measure the difference in water level between the return section of your sump and the water level in the display tank. That is the vertical head that the pump is working against.

02/23/2006, 08:42 PM
Thanks ChemE. The height I mentioned will be within a foot a what I said already.