Someone with LOTS of patience please explain my plumbing and pump problems

dmschiff

dmschiff

Member
First let me warn you of my overall plumbing ignorance and my inability to spell. I apologize in advance for any stupid questions. Yes , there will be many!
Here we go:
120 gal AGA with dual built in corner overflow overflow rated 600 gph each
2 megaflow kits
Approx. 40 gal diy sump/fuge
mag 18 (which I believe is only pumping 1000 at 0 head and about 750 as plumbed. --another story for later--working on that)
What is the recommended water level of the DT? Should it be to the top of the slits in the corner overflow? OR Should it actually go over the top of the outerwall of the overflow?
At this point the outerwall of the overflow (with the slits) is not allowing enough flow into the corner chamber where the drain is located. Therefore, we had to cut back the drain flow.
Why isn't it keeping up? I assume that the surface area of those slits should be enough to allow for the 600 GPH drain or else why would anyone buy this product?
I know I read in one of SCSInets posts that you should never use the ball valve to cut back the drain (except for maintenance) so what is the alternative?
If anyone is brave enough to take on the challenge of explaining this much to me I'll probabley have more questions later.
Thanks!
 
hammerhed7

hammerhed7

Active Member
the DT tank level should be around 1/2 of the height of the teeth (holes) in the overflow, this will vary but generally if you use 1/2 the height of the teeth or less, the better the surface will be skimmed, the higher the water level the slower it will skim the surface, I know this is true with external overflows I have not used a megaflow, but I don't see why this would be different with the internal overflow. Some megaflow owners may be more helpful than me with this.
Secondly, each overflow should handle the 600 gph without a problem, also the mag drive 18 is rated at 1800 gph at 0' this is more than enough pump, my guess would be this is a plumbing issue. Does the overflow catch up if you dial down the pump with a ball valve? Double check the plumbing, and set the DT water level at using 1/2 of the overflow teeth. Also, does the water level in the sump stay consistent? Try to post some pics, I am sure someone here can help.
 
indyws6

indyws6

Member
Greetings

I'm not an expert, but I have an AGA tank with a Mega Flow corner overflow unit. HAMMERHED7 is correct - the level of the tank should be kept at (approximately) the middle of the top row of vertical slots on the overflow. If it is higher than that, the surface will not skim well. If it is lower, then there will be additional noise coming from the overflow area of your tank. If it is REALLY low, you might be able to see the surface of the water below the top tank trim piece. (This won't hurt anything, but looks bad...). I assume that you know you can raise/lower the water level in the tank by raising/lowering the standpipe in the overflow chamber.
My tank is a 90G with a single overflow and I run a Mag 9.5 pump for my return. I have seen conflicting information; some state that the corner overflow units flow 600 GPH, others state that it flows 450 GPH. I don't know the correct answer (although I suspect that it is 600 GPH), but I do know that my Mag 9.5 works perfectly paired with my single overflow and does not require any "throttling" - on the drain or return sides. In other words, the overflow can keep up with the pump running at full blast.
Based on that, your experience should be similar considering that you have two overflows and a pump that moves twice the volume of water that mine does. Granted, there are other factors (head loss, plumbing configuration, etc.) but, in general, I believe this to be true.
My plumbing approach introduces some losses (2x 90 degree elbows, 2x 45 degree elbows and 3+ feet of head), which, most likely, brings the actual GPH flow down to the range of my overflow capacity. That, in turn, helps match the pump to the overflow and makes the system work without the use of a valve (for "throttling" purposes). You mentioned that your pump flow was significantly less than the rated capacity. If that is true, your overflows should have no problem keeping up. Without some detailed information, it is hard (and not real helpful to you) to guess at the problem. I am attaching a photo of my plumbing - can you do the same? It will help everyone understand your installation and, hopefully, provide you with better answers.
Apologies for the long-windedness of the explanation. I hope it helps...
Take Care,
Mark
 
groupergenius

groupergenius

Active Member
Originally Posted by indyws6
I assume that you know you can raise/lower the water level in the tank by raising/lowering the standpipe in the overflow chamber.
Yep, I like to keep the drain stand pipe a little low in the overflow area so the tank water is actually spilling/waterfalling in.
 
saltn00b

saltn00b

Active Member
what is a megaflow kit? a durso pipe stand?
what should your return pump be pushing at your current point of friction? (veritcal height, but how much lateral distance, kinks and turns?)
is there anything possible clogging your drains?
 
dmschiff

dmschiff

Member
The last few photos show the change we made to the return line. It is now 1 1/2 coming off of the pump and then at the T goes to 1 inch to each return.
You may notice we have some issue with the final wall of the bubble trap coming apart, but I don't how this can affect the over flows. At this point we have not started the skimmer.


 
saltn00b

saltn00b

Active Member
check the syphon break hole on the Dursos. on mine, it sometimes gets clogged with salt creep and have to make sure it is cleaned out. experiment with closing the hole completely to increase or decrease the flow rate accordingly.
 
groupergenius

groupergenius

Active Member
I still don't see why you would lessen the flow of the drains.

The tank will only drain as much water as your putting in it.
 
dmschiff

dmschiff

Member
Originally Posted by GrouperGenius
I still don't see why you would lessen the flow of the drains.

The tank will only drain as much water as your putting in it.
We turned the drains back because the overflow chamber drains faster than the overflow is refilling it. If we don't turn it back the water drops below the whole in the stand pipe and stops it completely. I suppose it will start to again once the overflow catches up but won't it quickly drop again? Not to mention the air that gets in...
We throttle the drain back enough to maintain the water level above the hole in the standpipe to keep a constant flow.
 
groupergenius

groupergenius

Active Member
Originally Posted by dmschiff
We turned the drains back because the overflow chamber drains faster than the overflow is refilling it. If we don't turn it back the water drops below the whole in the stand pipe and stops it completely. I suppose it will start to again once the overflow catches up but won't it quickly drop again? Not to mention the air that gets in...
We throttle the drain back enough to maintain the water level above the hole in the standpipe to keep a constant flow.
Sounds like the return pump is not big enough maybe. It's draining off faster than the pump can return it.
Try this. Pull the overflow (durso) pipes up a little higher so that the water level in the tank and the overflow area are the same. 1/2 way up the slots.
If you get a constant flow, then I would definitely say the pump is undersized.
 
juice_1080

juice_1080

Member
Originally Posted by GrouperGenius
Sounds like the return pump is not big enough maybe. It's draining off faster than the pump can return it.
Try this. Pull the overflow (durso) pipes up a little higher so that the water level in the tank and the overflow area are the same. 1/2 way up the slots.
If you get a constant flow, then I would definitely say the pump is undersized.
Sorry to jump in but from the sounds of what he is explaining....The water in corner overflow IN the tank drains to the sump faster than the water from the tank refills that corner, meaning that the overflow is not working all the time. If I am right (I don't know if I am) you probably have a clog in the overflow holes or something like that.
 
juice_1080

juice_1080

Member
I don't have a setup like this running right now but I am actually picking up the megaflow kit in about a week so I would like to see the outcome of this.
 
juice_1080

juice_1080

Member
I sold it for the same price I bought for and I will be picking up the new one in a little while. They have to order it for me because nobody seems to carry them around here. It was alot less than you mentioned before though $180 + the Megaflow standpipe kit.
 
waterworld

waterworld

Member
What are the cylinder like parts in the plumbing that look they are attached to the bulkheads? Are they check valves or something?
Also, I do not think you should have to throttle back the water from the overflow. It should open and water can only return as fast as it is pumped into the DT.
I am also in the process of pulling the trigger on a new tank after mine split a few weeks ago and am curious how the MegaFlows work for you.
WW
 
dmschiff

dmschiff

Member
I'm sure nothing is blocked since everything is basically brand new. I'll try raising the dursos, but agree that the pump is most likely not keeping up.
It is a mag 18. When tested in a wash tub with basically 2 feet of head or less, it only pumped about 1000 gph.
 
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