# 3/16 and 1/4 Rigid Hose for dosing container



## twobytwo (Oct 25, 2014)

I'm looking for 1/4" ID tube (*NOT* flexible hose). Something to use for dosing containers. like this:
http://www.bulkreefsupply.com/1-4-clear-acrylic-tube-16-long.html

I went to a big als mississauga and they had 3/16", but not 1/4"...
Reefsupplies is the same - they sell 3/16 ID, which goes _inside_ a standard 1/4" airline.

Do people usually get 3/16" and insert _inside _a 1/4" airline? or is it more common to see 1/4" inside the container. My airline push connect fittings are all for 1/4" hose so I figured that's what I should use to be able to easily connect the rigid line to soft hose, and then to my doser.

If a 3/16" rigid is inside a 1/4 hose, how confident can I be that it wont leak? Do I need to seal the connection with a glue or something?


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## nc208082 (Jun 27, 2013)

Funny your posting this. I went out to buy the exact same thing today. I bought the 3/16 size as it was only 2 bucks. The 1/4 hose fits perfect and snug over the 3/16 tube. I don't see a need to glue and totally seal it. I'm just gonna slip it over and run it like that.

For 1/4" tube I'd go direct to plastic world for that if still after.

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## nc208082 (Jun 27, 2013)

Just to clarify something, is the 1/4 ID a typo? Should it mean 1/4 OD?

1/4 ID would be huge. The reason asking is the link you posted is 1/4" OD.

I went and bought the 1/4" OD just as well to see which would be better. It would work with the push fittings your planning on using. Turns out my tubing is actually 3/16 so im going to use the big als one.



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## twobytwo (Oct 25, 2014)

Yeah,m even I got confused. They list the pipe as 3/16 and then 5/16 but the label doesnt indicate ID or OD. 3/16 fits inside a standard airline tube, 5/16 is too big. I wanted something with the same ID as airline, so I could connect them with standard push fittings.

I guess I'll use 3/16 inside the airline and call it a day.

New question: Should I be using check valves with a dosing pump?


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## nc208082 (Jun 27, 2013)

As long as your dosing lines aren't submerged I.e. they remain above water level at all times you should have no need for a check valve.

If you want to add for extra security then make sure to clean often so it doesn't get clogged.

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## Crayon (Apr 13, 2014)

twobytwo said:


> New question: Should I be using check valves with a dosing pump?


I'm debating that one, too. Except, here is a question: what are you trying to prevent? More of your dosing liquid from entering into the fish tank? Or the salt water back flowing into your dosing container?
Obviously one end of the dosing line is always submerged in liquid, or you wouldn't be able to dose.
Some manufacturers will tell you their rollers pinch off the tube enough that you don't need check valves.
Except GHL just told me their dosing heads may stop between rollers and might allow water to back flow into the dosing container..........
But you can't have check valves working both ways!
I am running 15 dosing pumps right now.
Alk 
Calk
Lanthanum
ATO
AWC x 6 (3 systems)
3 refrigerated feeding tubes
2 amino acid coral supplements

The only ones I am having issues with backflow are the refrigerated feeding, but I think it's a result of running the pump in reverse and not calibrated properly. Everything else is fine. All my tubes are under water in the tanks. However my dosing pumps are mounted up high, and that may help.
So to answer the question of check valves....I don't think they're necessary.


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## twobytwo (Oct 25, 2014)

I wrote a whole long explanation but it didn't make sense. Basically a check valve would be to stop air from siphoning into the out-put side.

On my ato, fluid comes from a reservoir, through a pump, and over the side of my sump (above the waterline). When the pump finishes, theres a bit of back pressure from the pump sitting at the bottom of the reservoir. The water in the hose isn't held exactly right at the opening at the output of the hose; theres a little bit of air that gets flushed back several inches. Next time the ato runs, the water just has to push a few inches in the hose first before it gets to the opening.

Can that happen on a doser? lets say I set the doser for 3ml/half hour. When it finishes, is there a chance that air backs into the line like my ato? My concern is that if more than 3ml of air is siphoned back into the line, the doser may not actually put anything in the tank if it cannot replace the fluid pushed back by the air.

Did that make sense?


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## Crayon (Apr 13, 2014)

Totally makes sense. And yes it could happen. What would happen if you moved your dosing container higher than the tank? Do you think it would continue to drip once the dosing pump stopped?
When we had the vertex doser in the basement and ran the lines upstairs to the tank, we never had any backflush or air getting into the lines. We would dose about 5ml and the fluid was right at the opening each time.
I'm going to do an experiment with my GHL dosers this weekend and see if I can get it to do what you've had happen with air receding into the tube.
Will report back.


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