rethinking plumbimg.....questions

[bergamer]

I dont have built in overflows so I am using a lifereef overflow.
but the problem is that I dont have enough change over of the water, and I dont like having the over flow on one side because when something happens and it gets dirty, it is harder to clean (unless I hook up my clear for life filter.
Is it possible to place 2 CPR 100 overflows on each side of my tank and run them both down to my sump?
if this is advisable? how do I connect both overflows to my sump?
(as there is only 1 hook up on the sump plate for 1 line?)
and what size pump would I need for a return? I have a mag 12 atm, what size woudl I need?
and what about the return line?
how large of tubing would I need as it would split to both sides of the tank
and finally with my current set up, if i lose power, my sump dose not overflow, but it gets kinda close to the top. I am thinking it should be the same as long as the overflows are at the same exact height.
but i have no experience with CPR overflows, so please enlighten me
how much do they sit in the water? are they shallower or deeper than life reef?
thanks

 

[bergamer]

I was thining of using a mag 18, which is 1800gph
the cpr 100 overflows are rated at 800gph, so if I had 2 of them, it would be 1600gph.
should I get a larger mag to be safer? or is this large enough

 

[scsinet]

First, your question of two overflows...
I am not sure you'd have success with this. It's unlikely that both will work together reliably. Because they rely on a siphon, they must be continuously fed with water to prevent them from "slurping." CPR CSOs use an aqua-lifter vacuum pump to draw the air out of the top of the siphon. This work great as it allows a broken siphon to re-establish, but it makes them slurp something awful when there is no water going into them.
If you use two of them, one will inevitably get more water than the other, and they will slurp. You may be able to make it work (in fact, you probably will), but you'll have to be constantly adjusting the height screws on them to keep things running right. I've never tried it, but I'd be curious to know how it works. Personally, I'd use one big one, like the 202.
BTW, buy at least one extra aqua lifter. They routinely fail, and you don't want to be stuck with no filter.
To figure out what size pipe you need, figure the area of the pipes. Obviously the wall of the pipes takes up some room but you can get close enough.
The CS100 uses a 1" outflow. Please, you math wizards don't shoot me for rounding pi to 2 decimals. The area of a circle is pi(RadiusRadius) so pi(.5x.5) = .785 sq in. You'd need twice that. So, your size pipe would be 1.5" pipe as pi(.75x.75) = 1.77 sq in.
As for your pump, when using any overflow, your pump needs to be rated at LESS than the total capacity of your drain system, not MORE. If you oversize the pump, the pump will get ahead of the overflows and empty the contents of your sump into the tank, slurp, then the tank will dump back in, over and over and over. So, if your CS100s are rated at 1600gph total, a mag 18 might work with a flow restricting valve on the outflow of the pump (do not put it on the intake side). Plus, you have head pressure reduction so you really will only be looking at 1200-1500 gph from it.

 

[bergamer]

wow, thanks.
I definatly do not want to hear any slurping.
is there any way around it?
I was thinking that a larger pump, with a ball valve to regulate it, would always send enough water back into the display. Thus thus the overflows would always have a constant water supply.
(as I would adjust the water pump to make sure it always kept the water level at a certain height)
I don't unerstand where my thinking is going wrong here?

 

[scsinet]

Neither did I when I started using overflows... but trust me.
You don't adjust the water level with the pump. Thats' what I tried to do initially when I first started in this hobby. It's basically impossible. No matter what you do, you cannot get it right and keep it that way, especially because outside factors constantly alter things enough to make either the overflows get ahead of the pump (good) or the pump gets ahead of the overflows (bad).
With CPR overflows, the aqua lifter draws water from the top of the siphon. If you deprive the overflow of water long enough, it draws enough water to empty out the bottoms of the siphons and air slurps in. This does not happen as long as the overflow is supplied with more water than the vacuum pump can move (which is 3gph, so no biggie). As long as that minimum is met, the overflow skims off whatever water is presented to it, quietly and effiently, up to the maximum flow of the overflow.
The overflow has a front edge where it skims the water, just as a normal drilled overflow would. That is what regulates the water flow. The water will (read: should) always sit at the height of that front edge because the overflow skims off everything above it's front edge. If you put a pump in strong enough to overwhelm the overflow, yes, the water will rise over the front edge... and over the top edge of the tank... and onto the floor...

So, you never try to regulate the water level with a pump. You regulate it by raising or lowering how far the overflow sits down into the water. CPR overflows have thumbscrews for adjusting this.
In normal operation, an overflow should never be operating at maximum capacity. You always oversize them. You maximize your investment by coming as close to, but not more than, the capacity. For example, it would be a waste to run a 1200gph overflow at 600gph, you want to run it at ... say... 1150gph. That way, the overflow is always getting enough water to keep from slurping or air-locking, but not too much to overwhelm in. The result: Your system works quietly and flawlessly.
Therefore, if you want to oversize your pump, you can do so and put a ball valve on the output of the pump (I stress again, not the intake unless want to hear what a burned up pump sounds like) and crank it down to a level your overflows can handle without overwhelming them, but you don't want to go crazy. Don't try do dial a 3600gph pump back to 1000gph. If you have two 600 gph units and you use a Mag 18, you're going to be pushing how far back you should really dial it, but you'll probably be okay. Using valves like this artifically raise the head pressure of the pump and increase wear and tear. You're probably already raising the water 4' to return to your tank, so you are only dealing with something like 1400gph anyway.
Just for your information, overflows like the ones CPR makes are never totally quiet. You always get a little "slurpage" from the back of the overflow where the water goes down the drain. This is where many newbies mess up. They try to put a valve on the drain line to keep the back of the overflow box full to stop air from slurping in, and they end up wtih a flood. Don't try this. CPR overflows come with a little rigid piece of plastic tubing that you insert down the drain line that lets a little air quietly in. It makes it much quieter, as well as using the sponge that comes with it.. just remember to rinse it often.

 

[bergamer]

i get what you are saying and so basically it is impossible to functionally run 2 overflows at the same time!
as theoretically it should work, but practically doesn't work bc of unknown fluctuations?
do you have any recommendations for U tube overflows with a small box.
atm I have alife reef and it works great, but the box is so large and ugly. which is the reason why I wanted the CPR. Then I guess I will just get ojne large overflow rated at about 1600gph and do you suggest a mag 18 or can I get away with something smaller?

 

[bergamer]

bump

 

[scsinet]

I've never used U-Tube overflows so I don't know.
You can just just about as small of a pump as you want. You can run a 1500 gph CPR 202 with a 200gph pump if you want... although it's a waste of money on the big overflow. I think you're doing things backwards. First, determine your desired flow. Next, size your pump for that, measure your head, and figure your GPH based on that. Finally, buy the an overflow with a capacity of greater than that GPH.