DIY Dosing Tips (for drop by drop dosing)

[Dennis Cartier]

I recently added RS Coral Colours to my tank, but found that with a low drip rate, I would get a lot of precipitation on one of the additives. Essentially the additive was evaporating before it had time to drip into the water column (I am adding 1 drop every 3 hours or so). I had seen a product from Pacific Sun years ago that claimed to address this situation. It was a dosing module that had acrylic tubes that extended into the water surface and had a smaller tip inside the air tight volume of the tube to stop evaporation. I figured that is what I needed, so I decided to build a DIY version.

I thought I must have something on hand to use for this? Ah, yes, my bag of 10ml syringes. A bit of staring at them and I had a plan.

1. Take a syringe and remove the plunger completely.
2. Pull the rubber stopper off the plunger.
3. Drill a small hole through the rubber stopper.
4. Cut a small piece of silicone tubing with a very small gauge hole in it (<1mm).
5. Pull the small piece of silicone tubing through the stopper. I used part of a small nylon zip tie (not pictured) to feed through the hole in the silicone tube and pull against the end.
6. Put the stopper back into the syringe backwards from normal operation.
7. Push the stopper to the bottom of the syringe with a piece of 1/4" PE tubing.
8. Attach a barb fitting to the luer on the syringe.

Here are 4 heads in various stages of completion. Sorry about the image quality. The shadows make it look out of focus, but it is not really.

A close up to help show the actual bits better.

... and the installed version. This is on a frag tank, so it is really hackish. The white on the syringe tube is condensation. At first I thought there was a ton of precipitation and pulled the tube holders off to examine, and nope, no precipitation. Yay!

This also keeps your tips dry even when the water rises when the return pump is off. No back siphoning possible.

Dennis

 

[Retro Reefer]

Nicely done

 

[Cory]

Thats genius!

 

[Billdogg]

Very nicely done. I hope you don't mind if I "borrow" your idea!

 

[CuzzA]

How or what device are you using to achieve such a low drip rate?

 

[Dennis Cartier]

Nicely done

Thats genius!

Thanks guys!

Very nicely done. I hope you don't mind if I "borrow" your idea!

Please do. After all I borrowed the concept from PS.

Dennis

 

[Dennis Cartier]

How or what device are you using to achieve such a low drip rate?

I use a Masterflex Digital drive (7523-60) in dispense mode. I installed 4 heads that take size 16 tubing onto the one unit and have it set to dispense 0.176 ml per cycle. This corresponds to the amount of RS Coral Colours that I need to dose to balance the 2 part that I dose in 1 hour. I have my timer for my 2 part set to turn on in 1 hour blocks and the RS CC pump turns on, dispenses and then counts down until the next dispense cycle, which I have set for 3650 seconds. As my timer for the 2 part operates in 1 hour blocks, the RS CC pump gets turned off before the count down finishes. My 2 part pump is a much newer Masterflex drive (7522-20), so it can dose in a 0.1 ml / minute rate so I run it for long periods to get my desired 2 part dose. Each hour of operation for it doses 6 ml of 2 part.

The one challenge I had with this setup, is that the dispense cycle only triggers when the start button is pressed. What I did was jumper the start contact on the D-sub connector on the back of the drive so that every time the pump is powered up, a dispense cycle is started. Works great!

I could set both pumps to work in dispense mode and dose 24x7 at a very slow rate with pauses between doses, but that would require a lot of calculations to get the ratio right, and previously I was worried about too low of a drip rate evaporating too fast. If I switched the 2 part dosing to using these types of tips, one of the concerns would be eliminated.

Dennis

 

[PacoPetty]

Brilliant!

 

[Dennis Cartier]

In a recent thread (Dosing container hole?) I posted about my dissatisfaction with the method that Red Sea suggests to allow dosing directly from their Coral Colours bottles. In short, they state that you must leave the lid ajar to allow for air to enter the bottle as fluid is removed by your dosing pump. In my case I am removing a very small amount of fluid per day (~ 1.32 ml), so leaving the lid ajar will result in significant evaporation of the contents as a bottle will last a long time at my dosing rate. While the evaporation is occurring, I would also worry that the remaining contents is going to be altered by the exposure to air either by being more concentrated or oxidized depending on the chemicals in question.

So I needed a way to allow me to dose a small amount daily, but leave the bottles air tight. My normal way of accomplishing this is to put a second 1/4" bulkhead into the vessel with a check valve inserted to only allow air to enter the dosing container and then have the back pressure of the check valve to seal the dosing container after the vacuum created by removing fluid has been equalized. However the Red Sea bottles that include the built in dosing setup don't really have any room for a check valve to be easily added. After thinking about the issue for a bit, I think I have come up with an easy solution.

To allow the dosing pump to draw fluid without creating an ever increasing vacuum, I will be implementing the following setup inline with the dosing line between the bottle and the pump.

The method of operation is:

1. Loosen the lid on the dosing bottle.
2. Pull the plunger on the syringe out drawing the fluid into the syringe.
3. Tighten the lid on the dosing bottle.
4. Repeat step 1 when the syringe contents have been dosed after xx days.

This will allow the volume of the dosing container to decrease as the fluid is reduced. In the mock up I am showing a 10 ml syringe, but I plan to use a 60 ml one when put into use. This will allow about 45 days of dosing before I need to refill the syringe. There are also 100 ml and 200 ml syringes available that would allow for long periods before the syringe would need to be refilled.

Another idea is to use an IV bag with a luer lock on it and dispense directly from it and not use the RS dosing bottle at all (and no syringe). That idea would probably still require some means of keeping the IV bags shielded from light to prevent any effect to the contents from light exposure.