air trapped in dosing pump line

[GainesvilleReef]

Your tubing is stretching on the input side and letting air in. The hard RO tubing only works well on certain pump connections like the BRS pumps. Unless it fits well and is screwed down it will change its shape to the connector and will loosen up. I use good quality silicon air line tubing on both sides the suction does not constrict the tubing enough to cause a problem on short runs. I have one tubing run about 25 ft.

 

[mcarroll]

It is airline, not RO tubing, but I think I'm with you cuz it is really tight and probably stretched.

I'll check the LFS for some silicone tubing, but I dunno how I feel about not being able to see if air is accumulating....ever seen clear silicone?

 

[GainesvilleReef]

Tom's aquatics makes an almost clear silicon tubing that you can see bubbles in. That's what I use. I order it online. I think it's a few bucks for 25ft. The silicone does not kink and keeps its shape over time. You would also be surprised how well it works in RO connectors. You have to give it a good tug to get it separated from the connector.

 

[kevinsmixed90]

mcarroll, you might remove the cover from the dosers ond see if there is a proper seal at the "head part" of the dosers. Having air on the intake side can only come from the intake line which you said was not leaking or the pump head itself. also you might benefit by drilling holes in the gallon jug lids and put the intake hoses through into the jug to keep out co2 and other impurities.

 

[mcarroll]

Good thoughts!

I'll definitely take a look inside to make sure all is well.

I go through those jugs pretty quickly so I'm not too worried about impurities. I will be though if/when I start making up Ca and alk in 5gal buckets again! [emoji106][emoji3]

The hole in the lid is a good idea if someone is concerned about that, but remember that air has to be able to get into the jug or eventually the action of dosing will create a vacuum that will interfere with performance or even prevent dosing at all. (found this out on my original dosing setup a few years back [emoji1]) if you do holes in the lids then they either need to be bigger than the dosing lines or you need second holes for air intake.

 

[mcarroll]

I can't get a pic of it as my phone won't focus on the airline tubing - too small - but I finally have some proof that (at least some of) the air is coming out of solution vs. some other source: the alkalinity line is covered in micro bubbles right now. There are far fewer in the calcium line, but I see them there as well.

I'm dosing every hour, 23 hours a day now - that seems to have cut down a lot on the amount of air accumulating so that the doser can do its job properly. Before, it was pretty regularly getting to the point that it would mostly be spewing air vs actually dosing. Now, testing verifies that it's dosing much more consistently.

I'm still puzzled why I'm seeing this issue (bubbles "precipitating") at all but, apparently, the vast majority do not.

Do most people tie down their dosing lines? Maybe the little bit of shaking that occurs while the pump runs is enough to knock some gas out of solution?

 

[Randy Holmes-Farley]

You see the air bubbles before the pump, or after, or both?

 

[mcarroll]

More on the intake side than the output side, but both.

 

[mcarroll]

Just as an experiment I bought a gallon-size ESV B-IONIC set. FYI, I dilluted it down to about 1/3 strength with my usual RODI water so I wouldn't have to change my dosers from their Recipe #2 settings (and then have to change them back after the B-IONIC is gone).

Since then the air in the dosing lines has cleared up completely. It's been a few weeks, but I just noticed today that the lines are completely clear of microbubbles.

So since I changed almost nothing but the media, I guess that implies something about my calcium chloride AND my sodium bicarbonate (various brands of each) that would cause these microbubbles...but I'm not sure what?

Interesting, but no less mysterious!

 

[Randy Holmes-Farley]

Maybe it happens for the same reasons that salt water froths easier than RO/DI water (and your decreased concentration is more like RO/DI than before). The reasons for this aren't tottaly clear, but I discuss it here:

http://reefkeeping.com/issues/2006-08/rhf/index.php#6a

 

[mcarroll]

The dilution was an attempt to match the concentration so it should be pretty close but probably not exactly the same.

You still think this may apply though? If I've understood ESV correctly, there are more elements in their two part then in my (your) old recipe number 2 mix...

 

[mcarroll]

(Got a 404 in the app-got to a place I could edit the URL tho.)

 

[Randy Holmes-Farley]

The link works for me, but you might try this one to the page as a whole
http://reefkeeping.com/issues/2006-08

then scroll to

Why does skimming work better in saltwater than in freshwater?

 

[Randy Holmes-Farley]

The dilution was an attempt to match the concentration so it should be pretty close but probably not exactly the same.

You still think this may apply though? If I've understood ESV correctly, there are more elements in there two part then in my recipe number 2 mix...

Ah, sorry, I misunderstood what you were diluting.

Not sure what the difference is. It might even be organic surfactants leached from the plastic containers.

 

[mcarroll]

The link works for me, but you might try this one to the page as a whole
http://reefkeeping.com/issues/2006-08[...]

I think it was a bug in the Reef2reef app....looked like for whatever reason it butchered the anchor link in translation. Weird.

Now we have a mystery within a mystery. LOL.

 

[drawman]

Well sorry to rehash an old mystery but I've been getting something similar that is quite annoying on my 30 gallon. I guess I've noticed air bubbles in dosing lines on my 60 gallon tank but it hasn't really messed with dosing and Ca/Alk have always been spot on.

However, I am getting a ton of bubbles on the output side (haven't paid as much attention to the input side but they could be there as well). With a smaller tank these bubbles are really making it hard to keep alkalinity consistent. I will check all connections tomorrow but I remember them being quite tight. Any suggestions?

I have thought about diluting the alkalinity solution and dosing more if I can't get a fix so at least things will be more even over time with air bubbles.

 

[reeftilldie]

I'm using 1.1 ml BRS dosing pump and having same issue. Air bubbles seem to get trapped in a few days right under output side . I have to remove the tubing and feed it with full RO and plug it back in ( and yes, this is so annoying ).
I'm suspecting that the feeding line with hard tubing get stretched? if so, i need to change to silicone tubing on intake side as well, the problem is i need to get an adapter to connect the silicon tubing to hard tubing (because dosing container has push connect bulk head and can only be used with hard tubing).
Any suggestions anyone?

 

[mcarroll]

Well sorry to rehash an old mystery but I've been getting something similar that is quite annoying on my 30 gallon.

I still don't understand it, but mine turned out to be related to the brand-new Lee's airline tubing I had....once it became "seasoned" the micro-bubbles stopped.

 

[Randy Holmes-Farley]

Peristaltic pumps cause a pressure reduction on the intake side just before the roller bar. If you are drawing the water up significantly, it might be enough to pull gas out of the dosing solution. Reducing the height difference may help.

 

[drawman]

Peristaltic pumps cause a pressure reduction on the intake side just before the roller bar. If you are drawing the water up significantly, it might be enough to pull gas out of the dosing solution. Reducing the height difference may help.

For my setup the height may only be about a foot and a half from the dosing solution to the intake. I am seeing some pretty significant dry areas not just a bubble or two. Could this still be gas coming out of solution?