Water level drops when pump is on

[schoolslave]

I just finished my build the other day and whenever I turn the pump/pc on, the water level in the res drops by about 3-4mm.
I let the PC sit unused for a day yesterday and noticed no change in the water level, I also let it run over night and apart from the initial drop nothing happened.

Is this normal?
I checked for leaks multiple times and couldn't find anything....

[MpG]

Yes, absolutely normal. Also the reason why you should be careful when topping up the reservoir when the system is running - you don't want it to overflow when you turn the computer off.

[Alexandr0s]

That's quite normal when you do a liquid cooled setup. There is still air stuck in the loop, which the pump is moving around. When it ends up in the reservoir the water levels will drop a bit. There's really nothing to worry about as long as there are no drops in or around your case. Just remember to keep the reservoir filled to a sufficient level.

[schoolslave]

Yes, absolutely normal. Also the reason why you should be careful when topping up the reservoir when the system is running - you don't want it to overflow when you turn the computer off.

That's the thing though, the water level doesn't go back up once the PC is off.

[Alexandr0s]

That's the thing though, the water level doesn't go back up once the PC is off.

Nope, like I said, it's air that's still stuck in your loop. Once it's out though, it wont go back in (a good thing ). Just keep it running for a while. In a few hours/days (depending on setup), the water levels should stabilize. Make sure the res stayed filled though.

[BeepBeep2]

Unless he has a small leak.

[bobruto]

@schoolslave: you must've slept in your physics class
http://en.wikipedia.org/wiki/Bernoulli%27s_principle

[WaterFlex]

Don`t worry Just some Physics

[gmat]

Once your loop is totally bled from air, the water level shouldnt move (or barely at all , accounting for elasticity of tubing). The level noticeably dropping means there is still air somewhere else in the loop (or a leak).

[Utnorris]

Actually, even once the air is out, the level will drop some due to the increase pressure in the lines from the pump pushing the water. This is normal and when the system turns off it will go back up. We are not talking a lot, but it still drops. If it isn't going back up, then it's air in the loops as others have said, unless of course you do have a leak, but I think you would have noticed that by now.

[8Fishes]

You know, for the longest time I think I've had a leak because of something similar that I heard elsewhere.

When the pump/computer is off, the water level rises a noticeable level.
When it is back on, it drops down to what I 'think' the normal level is.

I have noticed no leaks, and I think that if their is one, I would have burned out something by now since I have left it run 24/7 for a week. I honestly have no idea what is going on. I figure I have something like a microleak, and have an idea where it's coming from but I'm too lazy to break everything down to see if I can fix it. No water is coming out of anywhere so I figure I'l let things lie as they are.

[gmat]

If you just filled your loop a week ago, it's still cycling a few stuck little bubbles through especially if you have top mounted radiators and such.

[8Fishes]

That might be the case, but I've filled it about 2 weeks ago, but recently I've kept it 'over filled' to make sure all the air that is coming out stays out and is replaced with water. It also might be the fact that I THINK my EK res leaks, but oddly enough only leaks when I turn the computer off.

EDIT:

Actually scratch that, I KNOW it leaks because I see water develop at the top seal, and slowly drip out and down along the rest. I should probably fix that with some teflon tape.

[Alexandr0s]

Be careful with teflon tape. Most liquid cooling components are designed to deal with the pressure created by the extra thickness of the thread.

And guys, Schoolslave already said this build was recently put together, and his waterlevels don't rise when the pc is turned off. That leaves two viable options: Either it's still bleeding, or he has a leak.

[Waterlogged]

That might be the case, but I've filled it about 2 weeks ago, but recently I've kept it 'over filled' to make sure all the air that is coming out stays out and is replaced with water. It also might be the fact that I THINK my EK res leaks, but oddly enough only leaks when I turn the computer off.

EDIT:

Actually scratch that, I KNOW it leaks because I see water develop at the top seal, and slowly drip out and down along the rest. I should probably fix that with some teflon tape.

Um, how about something a little simpler like not filling it up so far? PTFE tape is near pointless on threads that use an o-ring, and in the case of an acrylic tube res. . .if you use too much of it, could cause catastrophic failure as it doesn't handle stress very well.

Be careful with teflon tape. Most liquid cooling components are designed to deal with the pressure created by the extra thickness of the thread.

Actually, the threads are there to allow the o-ring to do it's job. If it doesn't seem to be doing it's job, either tighten some more or check to see if it's making contact or damaged.

[8Fishes]

Probably more of the latter in my case.

I should get it looked at, but if I leave some air in the res, the pump's power causes a storm of bubbles.

[MpG]

That might be the case, but I've filled it about 2 weeks ago, but recently I've kept it 'over filled' to make sure all the air that is coming out stays out and is replaced with water. It also might be the fact that I THINK my EK res leaks, but oddly enough only leaks when I turn the computer off.

EDIT:

Actually scratch that, I KNOW it leaks because I see water develop at the top seal, and slowly drip out and down along the rest. I should probably fix that with some teflon tape.

Sounds like a case of too much liquid in the res + an air-tight top fitting = pressure build-up in the res which can try to force water out through any weak point. Do you hear any pressure release when you slowly loosen the top plug in the res?

[8Fishes]

I have a tube that connects to the top port and use it as a fill line. I keep the water about 2 inches, the rest is filled with air. I don't have the other end capped, or at least not tightly enough to create a seal. I figured it's probably leaking due to excess pressures though.

Is it bad to fill the res all the way out though? Like I said, If I don't keep it topped off a whole cloud of micro bubbles develop, and I know that'll lower my cooling efficiency.

[Waterlogged]

I have a tube that connects to the top port and use it as a fill line. I keep the water about 2 inches, the rest is filled with air. I don't have the other end capped, or at least not tightly enough to create a seal. I figured it's probably leaking due to excess pressures though.

Is it bad to fill the res all the way out though? Like I said, If I don't keep it topped off a whole cloud of micro bubbles develop, and I know that'll lower my cooling efficiency.

Head to a pet store or some other place that sells aquarium supplies and find the pump filter section. You want a coarse foam filter, sort of like these. Stick one about half way below water level and it'll kill the bubbles.

[Geezer]

If the water level drops fairly quickly when you turn the pump on and stays at the reduced level when you turn the pump off, it's most likely because you've forced air out of your loop and into the reservoir. This is a good thing. (If it drops quickly when you turn the pump on because you have a leak, you're going to notice fairly quickly.)

If you notice the fluid level in the reservoir drops when you have the pump off for an extended period of time, you either have a leak or you have an open fillport and are losing liquid to evaporation.

If you turn the pump on and notice that over a period of time (ie. hours/days as opposed to minutes) that the water level drops, it could be small pockets of air slowly working their way out of your loop or it could be a leak that only appears when your loop is pressurized. Standard leak testing procedures would apply just to be on the safe side but if you determine you have no leaks, it's likely just small air pockets being moved into your reservoir.

If the water level drops when you turn the pump on and goes back to "normal" when you turn the pump off, it indicates that you either have a fairly restrictive component in your loop that is creating pressure when the pump is on or you have a length of tubing that drains into the reservoir when the pump is off. Neither of these are a significant issue.

The "difficult" aspect comes into play when you realize that all of these different situations can play off one another. You could have a small leak (fluid loss), a fairly restrictive loop, air in your loop, and a section of tubing that drains into the reservoir when you turn the pump off. This would mean that the fluid level in your reservoir would seem to be all over the place.

As a result, the best thing to do is concern yourself only with the fluid level in your reservoir in one state. If you leave your PC running 24/7 with power-downs only rarely, focus your attention on the fluid level only when the pump is running. If you power down your PC regularly (ie. nightly) then focus on the fluid level in the reservoir when the pump is off. The goal is to eliminate as many variables as possible. By noting your fluid level during only one pump state (pump on or off, not both), things like fluid level changes due to pump pressure or drained loop segments are removed from the equation. Removing those, you only have to consider two things if your fluid level is dropping: you're forcing air out of your loop (good) or you have a leak (not so good).

[terente0081]

My water level also drops by as much as 1 centimeter, but it's due to restrictive loops, many pumps (lots of pressure) and tygon tubing, which is kind of elastic and visibly gets thicker when the pumps are on.