lets talk skimmer water depth height

This has turned into one of the most interesting threads around here in a while. And also a nice refresher course for me. Never been much of a fluids guy; I like structures and materials far more...

There's also a nice example of experience over education here also.

2 things I'd like to bring up:

Powerman, the one thing you threw me off with was the mention of the skimmer manufacture's recommendation on water height. IME, the manufacture gives a recommendation on the level of the water in the sump (ie - how deeply to place the entire skimmer). It's then up to the user to adjust the gate valve to set the height inside the skimmer body in order to obtain the "wetness" of the skimmate they desire. At some point, I interpreted your statement as the manufactures height recommendation is for the water level inside the body. Did I miss something here?

Lastly, when I was convincing myself about the amperage draw of the pump v. flow, this is the equation I ran across:
Ph = q ρ g h / (3.6 10^6) (1)

where

Ph = power (kW)

q = flow capacity (m3/h)

ρ = density of fluid (kg/m3)

g = gravity (9.81 m/s2)

h = differential head (m)

This does account for head loss, but due to the nature of a pump curve, the flow rate will offset the head loss. Of course, one could consider the pump efficiency as an additional term in the denominator of the equation. Just thought this might help some people out in their thinking, actually seeing the equation.

 

No you generally have it. Everything does not have to be presise. So setting the water depth the skimmer is in has a range... but you want it at a certain place. From there you can adjust the water level in the skimmer with the outlet valve to give you the skimmate you want. There is a recomended water level the maker will give for the skimmer.... usually that will be around the bottom of where the transition starts or the bottom of the neck.... but there is a range for that too. Some makers actually mark it on the body where the water/bubble line should be.

So if you set you skimmer all the down... 10" of water.... yet you want dry skimate... then you open the valve, but you can't get the water level in the skimmer body low enough to give you dry skimmate.... So you raise up the skimmer... until you get what you want.

Think of skimmer depth as gross adjustment, and water level and outlet valve as fine tuning. You get it in the ball park with depth, you get it fine tuned with outlet valve.

 

Hi guys, not sure if anyone will get a notification on a thread this old but hopefully someone can help. This will be a little long so bear with me.

I have a Red Sea Max 650. I replaced the skimmer that came with it about a year ago because it was square and difficult to clean all the grooves in the cup and it was really loud. I replaced it with a Hydor performer recirculating. I made a rookie mistake and only measured for the height requirement and forgot to measure for the length and width, so it did not fit in the skimmer section of the Max sump. So I propped it up so the pump that was too big sits on the wall next to it.

With the Max, I do not have the greatest control over the water level in the sump because of the way the overflow works. It's EXTREMELY sensitive and if I were to manage it to be at a constant level, I would literally have to check it every hour or more and that's not possible. When it backs up a bit into the tank because the overflow needs to be opened slightly, the automatic RO top off in the sump drains to compensate for the lower sump level (thinking its evap) so then when I go to adjust the overflow, the sump level raises an inch or two because the overflow has been adjusted. It's a constant battle. So the issue I've been having is when the water level in the sump is high, it causes the water level in the skimmer to raise and then it overflows and water goes everywhere, including over the back wall of the sump, and it leaks out onto the floor behind the tank. With a tank that big it's not possible to move it so its nearly impossible to clean behind it or under it when that happens. Especially with how often it's been happening. I don't know if it's because the air is dryer now so evap is happening more rapidly than during the summer or what but it's happening all the time and the cabinet is a complete mess from the skimmer overflowing and splashing and spraying everywhere. It's driving me crazy because I pride myself on a clean tank and equipment.

I was told operating depth with a recirculating skimmer doesn't matter but I think that's only the case if I can keep the water level in the sump constant correct?

I've been looking into getting a skimmer that fits properly in the space provided, which would help when it overflows, it would be about 6 inches lower, so the water probably wouldn't go over that back wall. But again, the ultimate question is, if I can't keep the water level in the sump constant then it will still overflow if the water level gets too high no matter what skimmer I have right?

Is there any skimmer out there where the water level around it wouldn't matter? I've already thought about moving it into the more open side of the sump where I have macro algae growing and my extra rock, etc. but the water level would be exactly the same so that doesn't really help.

All of the water pressure, pump power, etc. that y'all talked about in this thread is way over my head lol, so I guess I just need help with my unique situation.

Thanks in advance for your help!