Didn't realize this would be so long, it took a while to write but I hope it helps.
Hey Solov,
Solov said:
As for max flow Don, I agree that I should add closed loop on top of that 1800 from sump (1400) and refugium (400).
Firstly, maybe you just got your pump figures mixed up but a mag 7 will only give you 700gph at 0 head pressure (remember more head pressure will decrease you gph, as will elbows). Also find out how much head pressure your chiller will add, it might not be much but it could. The guys at marine depot told me about 1ft for the jbj that I will be getting next week
.
Solov said:
What I got from RC calculator for 1800gph is:
27 inch overflow length!!!
And 1.75" drain pipe diameter...
Secondly, the calculator you used on RC is assuming that all the water is going thru the drain below the tank which is not the case with what you are doing. If you want 1400gph going thru the drain pipe down to the sump you have to put in a drain pipe diameter for it. Now let me touch on the overflow length part because I think this is also important with your baffles in the sump which I will talk about later. The longer your overflow length (meaning going from left to right or horizontal distance) the easier the water can flow over the side of the overflow or thru the grating (you want enough grating openings as to not impede the water flow). This has nothing to do with the way the water exits thru the drain pipe/standpipe. So what do I mean by easier flow, well say you have a certain amount of water volume..for example 10 gallons. And this water is being sucked thru some sort of a channel or waterway. The narrower the channel, the higher the water height and velocity going thru it. So if you have a wide channel the water will be able travel slower, be less turbulent, and water height will be shorter (though the latter is more important with baffles). So the recommended overflow length, while it is important, once you know why its important I'm sure you can work around it.
So I will assume now that you will be using a return pump from the sump at around 1400gph (you can use a mag 18 but you will have to redirect some of the flow back into the sump).
Solov said:
But then I won't be able to easily disconnect chiller if I need to, will I?
As for the chiller you can't do it the way you are trying to do it. What you are doing is giving the water a chance to go into both the inlet and outlet of the chiller (giving the chiller a lot of back pressure) and i'm not sure what sorta flow you would get thru it. You also couldn't control the flow going into the chiller, although a gate valve could change that you still have to worry about backpressure. You should first look and see what type of gph can go thru it, you don't want it too fast because it won't cool efficiently because of lack of contact time with the water but you don't want it too slow either because the water could freeze. If you main concern is removing it then you could plump it inline with you CL with some unions and when you take the chiller out, you would have to turn off your CL. But what I think you will probably want to do is tee off either your CL line or your sump return line with some gate valves and run one of the tee outlets to the tank or whatever and the other into your chiller and then run you chiller outlet directly to the tank, which is what I think is recommended. The chiller is more efficient when the water from it is being returned directly into the tank (as opposed to back in the sump - for example with the extra 400gph from a mag 18). If I was you (although I'm not doing this myself
) I would put the chiller on the CL line. Because the CL line is just inherently less dangerous of overflowing or drying out, and you don't have to worry about microbubbles (which I will talk about in a sec). By the way, the chiller can still have flow going thru it when its turned off. Its just not chilling the water anymore.
Solov said:
Umm... I think you're right, for some reason I was thinking that going over top would secure me from back syphon
but with pipe filled with water, it shouldn't make any difference whether it's over top or straight from bottom, right? (where's my course of physics...
).
Yeah on a CL this doesn't matter but with the sump return its crucial to worry about this. You can still have your sump return go low if you have a way to break the siphon. If your going over the back with the return then you can drill a small hole (1/16 in) near the water surface in the pipe. This will break the syphon when the water drains down to it. I wouldn't put it above the water because air can get in causing bubbles and the small water that drains out the hole will sound like a trickle.
Now I go on to a very very important issue, Microbubbles. With that sort of flow going into the sump (1400 gph) it will churn up a lot of bubbles no matter what configuration you will have the water entering the sump. If you don't design the sump correctly, the only thing that will save you is filter socks or filter pads plus foam blocks. To avoid that try to design you sump with the following in mind if you can. Kevinpo actually talked to me about this before I did my sump but I couldn't so I use filter pads now lol. Remember a while back
when I talked about water going over the overflow wall. Well the same applies to water going over baffles. The point of the baffles is to get rid of the air bubbles by allowing air to travel up to the surface and pop or hit the wall of the baffle while going over it and pop. The faster the water is going the less chance it will pop when it goes to the water surface, it will just go right over the wall. And the wall won't pop it if the water height going over the baffle is too high because the air will never come in contact with the wall (the bubbles will be reduced but not by much). As I said before the water height of the water flowing over the baffle and its velocity will be determined by the gph flowing thru it and the width (depth) of the sump. The wider the sump and baffles the calmer it will be for water to flow over the baffles. So build a wide sump! My sump around 10.5 in wide with a 1600gph flow and the baffles really don't help. Kevinpo had recommended a with of around 17 or more for me, so you decided.
Solov said:
Yeah, that's why I was thinking of separating completely (right now they are connected by 2 inches of space on top) and cut some overflow-like grate on chamber 2 too.
Lastly I really thought about this and I think you would be fine as long as
1) the first baffle is the tallest baffle
2) the stand pipe is taller than the first baffle
3) the overflow walls are higher than the stand pipe (obviously but I said it anyway)
I'm not sure if my thinking is right on this one but here goes. Remember for water to go into the overflow you have to pump the water back into the tank to above the overflow wall. So your overflow gph is limited by your pumps. If you turn off your pumps the overflow will stop getting water. Now, if the refug pump is off and return pump on then the 1400 gph will just drain down your standpipe and nothing will flood because the standpipe is below the overflow wall. The refuge water level will be at the standpipe level but this will happen anyway. If your refug pump is on and return pump off then 400 will be drained into the refug and back into the tank. In this situation, nothing will flow into sump because your standpipe is higher than your first baffles and the rest of the baffles are shorter than the first. Now it gets more tricky when both pumps are on. Assuming there is no clog in the drain, the main concern here is that you will overflow your sump because you are pumping the extra 400gph into the tank and some of that water might go down to the sump when it comes back into the overflow. I don't think this can happen because the first baffle is below the standpipe. So the water will drain into the refuge area filling it before it gets to the standpipe. And as long as the walls of tank and overflow are above the standpipe, the refuge won't overflow either.
If your worried, you could just build your sump with enough room to cover your back syphon and cover the volume of the water in the refuge area so if it gets pump dry your sump will not overflow but I really don't think this will happen.
In this line of thinking I'm assuming that you are really using the baffles in the refuge as separators for the chambers and not to stop microbubbles. I don't think you will have a bubble issue there because that water isn't mixing with air like the water going down the drain. And because the water level will be above the baffle height the baffles probably won't be effective bubble stoppers.
Paul
P.S. Mojo has a lot of experience so I would trust what he tell's you.
