Bubbles in the MLT out hose?

jphussey · Joined: 17 Oct 2012 Posts: 171

I'm about 60 min into my first mash. Running into a few problems.

I set the HLT to 149 and the MLT rose from about 137 to 145 and then just stopped.

I bumped the HLT up to 153 thinking it was just a 4 degree offset (it's about 50 degrees ambient right now) and the MLT didn't rise at all! We noticed there was a *slight* bend in the MLT hose as it run to the wort pump and there seems to be quite a few air bubbles in the MLT out hose. We straightened the hose out and the temp started rising, though this may be purely coincidental.

Should I see these air bubbles in the MLT hose, or do I likely have poor circulation? I have an exact Kal clone and the pumps are full open.

I didn't calibrate the probes, but my thermapen reads 150 and the MLT probe is reading 149/150 now. So the MLT did rise up to 149 and I have the HLT at 152 now.

My concern is really just these bubbles I guess. The flow from the hose on top of the grain bed appears to be flowing well, but this is my first brew so hard to tell.

My grain mill is set to .045 (I think. I used feeler gauges, but it was the first time I've used this mill or feeler gauges).

**kal** · Posted: Fri Dec 09, 2016 9:35 pm Post subject: Re: Bubbles in the MLT out hose?

jphussey · Joined: 17 Oct 2012 Posts: 171

SS Center Inlet March 816 Pumps.
Blichmann G1 20Gx3
Vertical distance is 2-3 feet (SS prep table with pumps on lower shelf)
Hoses attached to QD with the barb and then the female QD, like in your hoses construction articles.

I didn't get any pics or videos this time, but will check the fittings all around before going again. The air was definitely present the entire 90 minute mash, so you're probably right it was a loose fitting. Nothing seemed to be leaking, so figured it was all good to go.

I will calibrate the probes. But if my thermapen and the probes read the same, that should indicate they are calibrated, right?

**kal** · Posted: Sat Dec 10, 2016 3:04 pm Post subject:

One place I've heard this happen is between the QDs. The fit on some seem to not be that great. Some sellers seem to sell ones that do not mate very well. If you search this forum I remember talking about a few times in the past.

Kal

hbohnet · Joined: 22 Sep 2013 Posts: 33 Location: Canmore, AB

I had the same problem but with camlocks which i believe are worse than QD's. After 3 brews with trying different fittings/hoses I finally but straight barbed fittings on the outlet of the MT and inlet of pump and made it a hard connection. I used butterfly type hose clamps that can be easily removed by hand. When it is time to switch the hose to the BK simply undo the hose clamp and add the Camlock or QD back in. Solved the problem for me.

jphussey · Joined: 17 Oct 2012 Posts: 171

Interesting. I bought them all from Morebeer.com, so would assume they'd be decent quality, but I will mess around and see if something's off.

Do you think this is a matter of just tightening them down? Or if they aren't leaking liquid, would that indicate they are tight enough? Maybe I need more pipe tape...put about 5 wraps on each though.

Tennessee · Joined: 04 Apr 2015 Posts: 116 Location: Tennessee

Try tightening the clamps first. You may not know for sure until your next brew day when the grain bed is full and there's a restriction upstream from the fitting. The restriction gives a greater chance of pulling in air than just free flowing fluid!

jphussey · Joined: 17 Oct 2012 Posts: 171

This raises an interesting question. How tight should worm clamps be tightened? I can definitely still turn mine some more, but I didn't want to risk cutting the hose.

Should these be tightened until I can't pull the hose off or essentially as tight as it'll go?

**kal** · Posted: Sun Dec 11, 2016 3:10 pm Post subject:

jphussey · Joined: 17 Oct 2012 Posts: 171

I do recall that some of my worm clamps were slightly misshapen as I put them on, but figured as I tightened them down they'd round out. Might be worth a look. I got the same hose too...pretty much ordered verbatim what you've recommended here on the site.

I'll experiment with it next brew day.

**kal** · Posted: Mon Dec 12, 2016 1:43 pm Post subject:

jphussey · Joined: 17 Oct 2012 Posts: 171

Kal,

In tying two of my threads together from the first brew day, do you think that the crush of the grain might have anything to do with the bubbles in the MLT's output?

If the available liquid in the bottom of the MLT was too little, wouldn't more air get sucked into the hoses? I know that the flow rate on top of the grain bed seemed OK and I didn't experience a stuck sparge (I don't think!), so not sure if that nullifies this theory or not. I did do a full test of the system with water and oxiclean and I don't recall seeing any bubbles in any of the hoses during that test. So having a full MLT of grain was definitely a 'change' from that test process that could have induced this problem. And for what it's worth, I only saw bubbles in the MLT's 'out-hose', no where else. Wouldn't it be a little weird that just two of a whole batch of QDs was not sealing properly? Or would their poor seal be compounded and exposed by virtue of the limited liquid at the bottom of the MLT?

I'll do some controlled swapping and see if I can isolate the problem.

**kal** · Posted: Mon Dec 12, 2016 4:38 pm Post subject:

Ozarks Mountain Brew · Posted: Mon Dec 12, 2016 7:40 pm Post subject:

bubbles in the out hose for me was an issue with the pump having problems obtaining a good flow, this did just happen to me my last brew, once I got the pump regulated correct the bubbles went away and thinking back that day I had a gummy mash too, it would seem to me I wasn't getting a steady steam of wort going into the pump

fseider · Posted: Tue Dec 13, 2016 3:19 pm Post subject:

This topic is very timely! I am having the EXACT same issues with bubbles out of the MLT only. It has been very frustrating. Though I am still able to brew successfully, I know I need to get this resolved sooner than later. I have a (dare I say) close to a Kal Klone, but not exact. I have 1 C****** pump with SS Head and 2 March pumps - one with a C****** SS Head and one with a March SS Head and I am also using Camlocks instead of QD. (So a bit hesitant to ask about this issue here originally.) I get the exact same issue with any of these three pumps when connect to the MLT out, including the March 815 with March SS Head.

But I never suspected air getting IN from a fitting, and I would have thought with a non perfect fitting liquid would leak OUT. With this understanding I may have another troubleshooting route. And I would think this would apply to any fitting type - So would temporarily wrapping the fittings with something airtight help indicate if air getting in at the fitting is the issue? I would think that if the issue then went away, the wrapped fitting could well be the culprit. Hopefully maybe cling wrap and clamp, or a long rubber or other airtight sleeve and clamps should do the trick. I'd have to believe the issue would go way almost immediately.

Sound viable?

Thanks,

McGruber · Joined: 12 Aug 2014 Posts: 237 Location: Idaho

I had problems with this too; mostly with big grain bills. I use tri-clamp fittings which don't leak, vs Camlocks or QD's that potentially could a little easier - and yet I've still had this problem. I was also concerned that I was getting air in somewhere but couldn't figure out how that was possible from inside the MLT. I've even dismantled the components, cleaned and re-taped everything and still had problems. What I suspect the problem is, is what causes cavitation.

From Wikipedia (https://en.wikipedia.org/wiki/Cavitation)
'Cavitation is the formation of vapour cavities in a liquid – i.e. small liquid-free zones ("bubbles" or "voids") – that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities where the pressure is relatively low. When subjected to higher pressure, the voids implode and can generate an intense shock wave.' (That last sentence has more to do with the damage that occurs to pumps because of the bubble formation, and less with why we have bubbles in our wort).

I believe that as we are drawing on the mash with the pump, and the grain bed is resisting flow, that the gas in solution is expanding due to the negative pressure (relative to atmospheric pressure) and creating said bubbles. I've found that making sure my pump is fully primed and slowing down the recirculation rate has helped with bubble formation and loss of pump suction.

Ozarks Mountain Brew · Posted: Tue Dec 13, 2016 5:12 pm Post subject:

I agree

McGruber · Joined: 12 Aug 2014 Posts: 237 Location: Idaho

**kal** · Posted: Tue Dec 13, 2016 5:25 pm Post subject:

fseider · Posted: Tue Dec 13, 2016 8:34 pm Post subject: