doser back siphon

[AquaPhilNJ]

My top most doser is back siphoning. From the left doser heads 1 & 2. Where #1 is mag and #2 is calcium. I check #2 very often and I see the liquid inside the tube is visibly decreasing in height within the tube. The output tube is above the water of sump and the inlet tube is submerged in the calcium solution. I've always had this issue and consider the doser heads fully functional and seem to pinch tube tight. Tube is solid piece from doser into calcium solution; I've glued the cal tubing to the GHL tube nozzle adaptor, adapter to doser side not glued, tubing from doser to aquarium not glued.

Calcium is the one driving me crazy because can't keep as stable as I want, causing me extra work with testing and manually dosing. I wish I could compare to the doser below however not so easy because that one is being used for the KH Director, meaning most of those tubes are empty. The top doser head #3 may also back siphon but harder to tell because volume of liquid being dose is much higher, #1 and #2 only dose 1ml per day and back siphon maybe 1 - 2 ml per day.

I am using Red Sea CAL and MAG solution; I'm considering adding RO water into the dosing solution, if dose instead 10 ml a day back siphon of 1 ml per day should be unnoticeable. I was hoping for something better. Any advice out there? Thank you all : - ]

 

[Shirak]

Maybe some air is sneaking past the connector. I would get some small nylon locking hose clamps

1. 

 

[Shirak]

You said the connection between the doser and connector on the Cal side isn’t glued. If that is not an airtight seal the Cal solution will drop back down the tube into the container. You could test it with a twist tie or something and see if clamping the connection helps

 

[AquaPhilNJ]

You said the connection between the doser and connector on the Cal side isn’t glued. If that is not an airtight seal the Cal solution will drop back down the tube into the container. You could test it with a twist tie or something and see if clamping the connection helps

I'll keep my eye out for nylon locking hose clamps. I haven't done an in-depth search (so far coulnd't find) but not sure it exist for such a small tube it is 4mm ID tubing. I suppose maybe zip tie, but once that is on I can never get off without damaging doser GHL tubing. I def have twist tie can give that a try.

 

[sylvius]

I got this set from Amazon for the larger ones but reading this just checked and the smallest work on the doser union.

 

[AZMSGT]

Is the container that holds your Cal vented? If it isn’t vented it will create a vacuum when the pump tries to pull fluid.

 

[AquaPhilNJ]

CAL is in this blue bottle, so technically not vented. It's like a McDonalds drink with straw inserted (no bulkheads). Switched CAL bottle b\c felt safer with one solid tube vs red sea bottle with tubes connecting to bottom and top of lid.

In past I had the CAL in a red sea bottle, extra hole drilled for venting. Right now, MAG has that type of bottle, still back siphons. In past also tried having the lid completely loose figured would fix any venting issue, unless I'm mistaken? Perhaps a bigger vent hole is what I need. I figured this small one would work as seen in my picture MAG black bottle.

***
During dosing air bubbles rise from sump tubing end into doser head area. But back siphon is during non-use, so think that is not issue, also no forward siphon issue (that I know of : /)

 

[Shirak]

CAL is in this blue bottle, so technically not vented. It's like a McDonalds drink with straw inserted (no bulkheads). Switched CAL bottle b\c felt safer with one solid tube vs red sea bottle with tubes connecting to bottom and top of lid.

In past I had the CAL in a red sea bottle, extra hole drilled for venting. Right now, MAG has that type of bottle, still back siphons. In past also tried having the lid completely loose figured would fix any venting issue, unless I'm mistaken? Perhaps a bigger vent hole is what I need. I figured this small one would work as seen in my picture MAG black bottle.

***
During dosing air bubbles rise from sump tubing end into doser head area. But back siphon is during non-use, so think that is not issue, also no forward siphon issue (that I know of : /)

How tight is the tubing going through the hole in the blue cap? All you need is a small gap for air to get in. A peristaltic pump is capable of making a near vacuum. If it's causing a vacuum in the bottle during dosing that could be forcing air to get sucked past the tubing connector after it shuts off. So it's either most likely that or the tubing is just a tiny bit loose at the connector and it's dropping due to gravity over time as air enters into the tube.

 

[Vinny@GHLUSA]

Two issues:

1. Dosing nozzles are not installed correctly. You have the dosing tube only on the tip of the nozzle. It needs to be pushed in more so the tube is as close to the center of the nozzle as possible. The way it's connected now makes it far too easy for air to get inside and cause the problems you are having now.

2. Glue is being used...why?

If the correct tube is being used and it is pushed as far up the tube nozzle as possible, there is no need for any DIY work.