I think I know what you're seeing. I used to use a suction device to bleed my brakes -- it was always a real pain! It seemed great at the time (far better than pumping the brake pedal, which needed two people and risked 'toasting' the master cylinder), but take my advice, there's a MUCH better way.

There's something called a "PowerBleeder". You can get it from IPD as well as other sources. A big white plastic bottle, with both a pressure gauge and a air pump/handle. It creates 'positive' pressure, and pushed the fluid out the bleeders instead of sucking it out. No more disconcerting bubbles (although the bubbles you're seeing are really of no concern, since they're from air around the bleeder due to a loose hose, rather than from inside the caliper).

Anyway, take my advice, get the PowerBleeder! You'll thank me. It's a world of difference!

Are you using vacuum to pull the fluid from the calipers? If so, the small bubbles you see from air drawing in around the bleeder nipple threads is normal and not a concern.

If you have air in the calipers, it comes out fairly easily if you follow the suggested bleeding sequence AND assuming that your calipers were assembled properly. Search this board for discussions on that topic.

If you have air in the master cylinder because it is new or rebuilt, you probably need to 'bench bleed' it. Buy a short length of metal brake line, cut it in half, bend it into two "J" shapes, screw the ends into the outlets of your master cylinder such that the fluid is returned to the reservoir, and pump ~aggressively until there is no more air, then install the master cylinder.

If you have air in the system between the master cylinder and the calipers, there are a couple of spots that are really hard to clear of air. A pressure bleeder is the only reliable method. You can find various designs of pressure bleeders on line, at prices from $25 and up.

P.S. If your master cylinder is rusty or cruddy inside, pressing the pedal to the floor while bleeding pushes the rubber seals into an area of the master cylinder bore where they don't normally go. The rust and crud can trash them, rendering your master cylinder useless. Oh well, it needed replacing anyway.

Bleed sequence is 1. Left rear 2.Left front- top chamber ( top bleeder )
3. right front- top chamber 4.right rear 5.right front-lower chamber (other two valves, middle of caliper alongside pads)6.left front- lower chamber
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Gary Gilliam Sumerduck VA, '94 940 na Regina 150k, '86 240 180k

Generally you need to bleed one line at a time. Also there is an order to which line to bleed first, generally the longest ( rear right) to the shortest (front left). there are seperate pressure system (lines) so you do one at a time. As to the bleeders, you open as someone pushes the brake pedal down and close it before they lift their foot. Really you need to do some more reading before you continue, check the archives here and get a Haynes manual. Brakes are the most important system on your car make sure you know what you are doing.
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Patrick, '68 220, '83 245, '92 Eurovan (work truck).