Auto dosing liquid ferts - The Planted Tank Forum
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post #1 of 9 (permalink) Old 01-04-2016, 02:56 PM Thread Starter
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Auto dosing liquid ferts

I've been dry dosing and decided after building the iAqua to try using pumps to auto dose. Honestly dry dosing is quite easy, just measure out the ferts into pill containers when I do a water change, then dump the one thing in each day when I feed. But now I don't have to ask my neighbor to do it for me when I travel.

I'm seeing on issue and am looking for ideas. Here is a picture of my setup.



As you can see the Macro (left) and Micro (center/yellow) liquid drain back into the container over time. Since they only get dosed every other day I end up with some empty tubing each day time. Now I was able to measure it and it is about 10mL of liquid. So I could just up the amount I dose to account for this, but that doesn't seem right.

I'm using silicone tubing and it is a single piece. This drain back doesn't happen with the Excel. I don't think it is because I dose every day. I've check it and it never drains back. No ferts drain between the pump and the tank. The pump prohibits that from happening.

Has anyone else had the issue where the pickup tubing drains? I've thought of a couple ideas to address this, but would like other ideas.

1. I could try a check valve, but I really don't like them especially if it is sitting is ferts. I'm not sure if they would last.

2. I could raise the fert bottle to be above the pump, I think that would ensure that it doesn't drain back into the pump.

3. increase the dosing amount to account for the drainage.

Any other ideas?

thanks,
david

EDIT: I just remeasured the drained back liquid and it is 10mL, not 5 as I specified previously. I dose 50mL macros and 20mL of micros, so this is a significant amount.

Last edited by lovingHDTV; 01-04-2016 at 03:36 PM. Reason: fixed amount of liquid that drains back
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post #2 of 9 (permalink) Old 01-04-2016, 04:11 PM Thread Starter
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Some additional ramblings. Turns out that silicone rubber tubing I bought from Amazon has a high permeablility to gas. I suspect that this is the cause of the drain back. If gas/air can permeate the tubing it will allow the liquid to drain back into the bottles. The permeability coefficient of the tubing is rated at ~20,000. I guess I'll order some that is on the order of 1200 and see how that works.

For others out there, what type of tubing do you use?

thanks
david
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post #3 of 9 (permalink) Old 01-04-2016, 05:32 PM
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Maybe your co2 tubing you already have
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post #4 of 9 (permalink) Old 01-04-2016, 05:51 PM
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use auto dosing on 2 of my tanks, different types of tubing the pumps are suppose to stop drain back but i havnt had good luck. i found using one of the flat cheap style check valves work great.


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post #5 of 9 (permalink) Old 01-04-2016, 06:12 PM Thread Starter
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I just ordered some Tygon B-44-3 tubing. It is made for beverages and has a permeability of 270 vs 20,000. I'll update when I get it, should be a couple days from amazon. For the time being I opted to increase my dosing amounts by 10mL to account for drain back.

I'm still baffled as to why this is not an issue with Excel. Even now 3 hours after dosing micros and excel, at the approximately the same time, there are bubbles appearing in the micro tubing, but none in the excel tubing.

apha1172 do you have the check valve in the bottom of the fert bottles or just at their top?

david
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post #6 of 9 (permalink) Old 01-04-2016, 11:16 PM
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You might try putting the pumps at the same level or below the liquid containers. That works for me.
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post #7 of 9 (permalink) Old 01-07-2016, 05:20 AM
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i have them right below the outlet, i also have dilluted the solution and dose more also. this was for potential drainback and for inaccuracy


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post #8 of 9 (permalink) Old 01-08-2016, 12:17 PM Thread Starter
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Well I got my tubing yesterday and replaced my micros line, as it is easiest to see. After 15 hours there is no sign of bubbles in the line or any drain back. This tubing seems to work well. I just swapped out my macros tubing.

This is what I purchased:
http://www.amazon.com/gp/product/B000FMWSKS?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
I got 50 feet for $6.42, but I see now that it is $17 I guess I got lucky.

I have not had any issues with the Excel line. I didn't change it out as it appears to be working just fine.

david
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post #9 of 9 (permalink) Old 01-29-2016, 02:37 PM Thread Starter
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update:

The B-44-3 tubing worked great to keep the air out of the line, but after it sat for a day or two the pump couldn't get started again. The tubing was just too stiff for the little pumps. So I cut the b-44 in half and replaced the original tubing that came with the pump. That works, but it still allows air to get into the lines. Now it is less air because that piece of tubing is only about 5" long. Still wasn't happy and I don't like the tubing in pieces I prefer a single piece as it is less prone to failure.

I looked around a bit more and bought some Tygon E-3603, which has a low permeability coefficient of ~360 vs 270, but still much better than the 20,000 of silicone.

I've had it on for about 20 hours now and no sign of any air in the lines. I was also able to run the pump easily and the e-3603 tubing is made for peristaltic pumps. So it seems to be a good compromise and I'm hopeful my air in the lines problems are solved.

Here is a link on amazon where I bought it:

http://www.amazon.com/gp/product/B00QRET1W6?psc=1&redirect=true&ref_=od_aui_detailpages00
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