'gravel' sound in loop, help

[roller11]

I'm brand new to WC, so I'm benching my loop and I get this 'gravel' sound, like sand in ball bearings. I'm pretty sure it's air bubbles going into the pump, I can see teeny tiny bubbles in my res, but no bubbles in the clear hose connecting res to pump inlet. I'm benching a hydor seltz 30 pump, same thing happened with the MCP655 pump. There's no way I'll put up with this noise, so unless I can eliminate it, I'm back to air cooling. I really don't want to send WC parts back for a refund, but that's what I'm looking at right now.

I've been letting the loop run for two hours now, still get the noise and no leaks. Is this noise something that can only be minimized but not eliminated? Is this as quiet as it gets?
res= thermaltake cylinder w/alum base,
rad = standard thermaltake 240.

[jumper2high]

Could be a small air pocket trapped in the pump housing itself. Try tilting the case (while the PC isn't running) to one side or another to let the air pocket pass through.

[KILLER_K]

Yea tilt and shake and tap on the rad helps to get the bubbles and air pockets out. And i have squeezed the tubing and then let it go to surge to knock the air pockets a loose also.

[NKrader]

also when there is very little air in my loop i cant see it. as the little bubbles are moving so fast that i cant see em.. usually takes bout 24hours to bleed those out.

[MegadetHCl]

The sound may also be air escaping from the radiator, which has a lot of places where air pockets could form. Like two posters above have suggested, tilt the case from side to side, being careful to watch the level of water going into the pump's intake. If your reservoir is located above your pump, the air bubbles should be sufficiently purged from the loop in several minutes to significantly diminish the "gravel" sound.

[Sadasius]

Air in the pump for sure. Give it a day or 2 and you will not even see little bubbles stuck to the side of the res. Everything will hum along quietly.

[roller11]

I figured it out. The "tilt the case " worked for a different type of noise, a sharp 'rapping', that turned out to be air trapped in the rad, tilting fixed that noise. The noise I reported was tiny bubbles being sucked into the pump, bubbles I could see in the res created by turbulence. I proved this by replacing the res with a big bucket of water. With both the inlet and outlet hoses submerged, there was no turbulence in the water. No turbulence, no bubbles, no bubbles, no noise. In this config, I got the 'sand in ball bearings' noise for about 20 seconds after priming the loop, then noise was gone completely. So the res was the culprit, a standard acrylic cylinder about 5" high by 2.5 diameter with an inlet ascension tube and a cutout bottom outlet. Now that I understand the cause, I can get a proper res and return the one I was experimenting with. Seems it is critical to eliminate turbulence with baffles so those tiny bubbles don't make it to the res outlet. I'm thinking the double high XSPC type that mounts in the 5.25" DVD cage will be perfect cause it has plenty of room to add custom hand made baffles. Or possibly the single high since it already has an effective baffle. Comments?

[Waterlogged]

I've never really like bay res's, especially single bay's, they have to be filled to almost overflowing to keep from sucking air and double bays are just a masive waste of space. Get a good (Tt is not good) tube res and if you still have problems, use a course filter sponge (<something like that) from a pet store that sells fish supplies and push it in the res until it stops the vortex/sucking air.