Overview of Autodosing Methods

[Wasserpest]

Thank you Ted, your wish is my command! At least for a while so more folks have a chance to see it.

I received my peristaltic pumps and for some reason, they pump much less than I had figured. Probably my math that was off. I guess I can run them for longer periods, no big issue, just another timer.

[Naja002]

Originally Posted by Wasserpest

I received my peristaltic pumps and for some reason, they pump much less than I had figured. Probably my math that was off. I guess I can run them for longer periods, no big issue, just another timer.

What diameter tubing did You get with the pumps?

[Wasserpest]

I wanted one to dose about 0.2ml and another one for about 2ml per minute (for my 10 and 100gal tanks).

Like I said, that day I must have been a bit math challenged and messed up calcs and order. I ordered one with 3rpm and 0.8mm tubing (~0.06ml/min), and one with 15 rpm and 1.6mm tubing (~0.6ml/min). I guess slower is better than too fast though.

After some testing I used the faster pump with the smaller tubing to dose the 10gal tank for 1 minute (0.25ml) and the slower pump with the larger tubing is dosing the 100gal tank for 10min (2ml). I guess in the end it worked out alright.

The slower pump is almost silent, the faster ones gears make a bit of a racket. I really like the small form factor, just tape a little fertilizer bottle to the pump, add some hosing, a timer, and off you go...

[Naja002]

Hey Wasserpest,

Did you have any problems connecting tubing to the tubing that came with the pumps? I got the 1.6mm tubing and looks like it comes with 1/16" hose barbs. I'm just wondering what You did for tubing from the ferts to the pump and from the pump to the tank......?

Also, You can adjust the dosage amount by diluting the solution more. In other words, my 120g setup would need 12ml/day under the PPS-PRO x 30days=360ml. A 20oz bottle holds roughly 591ml. So, 18mlx30days=540ml. 18ml divided by 1.5ml/min=12min cycle. This of course can be adjusted against actual output. That's my basic game plan at the moment.....

[Wasserpest]

I had some Norprene-like tubing from a friendly fellow member, as well as the usual air "Mini tubing". It fits alright, since there is no pressure involved it doesn't have to be extremely tight.

Diluting would be necessary if they pump too much, that's correct. I want to dose concentrated solutions, I think they don't degrade as fast as diluted ones.

[Naja002]

Thanx! I haven't received my pumps yet, but I did just pick up some medical grade 02 tubing, bubble counters, tank and a couple of regulators from a landlord that rents the place behind me--all Free. Now I just need a prescription to get the tanks filled. Anyway! the 02 tubing looks like a smaller diameter, so it may work. Don't really like the fact that its clear, but we'll see how it goes.

The solution can be diluted if it pumps too much or too little by adjusting the cycle time. In the end--its all about getting x-amount into the tank. Mine are estimated to run 1.5ml/min. At 0.25ml/min I think You've got a large margin of error!

[scolley]

Hey, great work WP! It's too late... but I still want to throw in a vote for sticky too! Really!

This is an outstanding starting point for someone considering autodosing. And for those of us that is has been successful for, that can make this hobby a whole lot easier.

Great job!

[Betowess]

Congrats on the sticky. I remember reading somethin Sergio said about getting the flow at the rated amount if the peristatic is set for full output. But if you opt for a variable flow unit, the ouput was not as consistent when setting the speeds. So the long and short, don't order a variable output, just use a timer or dilution to get one's desired ferts in the tank and use a one speed (flow) unit.

[SuRje1976]

Originally Posted by Betowess

Congrats on the sticky. I remember reading somethin Sergio said about getting the flow at the rated amount if the peristatic is set for full output. But if you opt for a variable flow unit, the ouput was not as consistent when setting the speeds. So the long and short, don't order a variable output, just use a timer or dilution to get one's desired ferts in the tank and use a one speed (flow) unit.

That's exactly right. I had a bit of an issue with getting repeatability with the variable flow pumps the further I deviated from full throttle. SO, I run them at full throttle and adjust the time they run for instead. Pretty simple to do with the timers I'm using (X10 macros), but if you are using a timer that is adjustable in increments of minutes, etc, you'd just need to adjust the concentrations of your stock solutions accordingly. There is, in my opinion, NO need to spend the extra $$$ on the variable flow pumps.

Great thread!

[gmccreedy]

Originally Posted by SuRje1976

There is, in my opinion, NO need to spend the extra $$$ on the variable flow pumps.

Great thread!

And this coming from a guy who is not afraid to spend $$$ on techy devices....

I almost fell over when I read this. Had to re-read this a few times for it to digest...lol.

[lopez_316us]

Wow! How I didn't see the before...

Really helpfull~~~!!!!

Thanks

[Wasserpest]

You are welcome, thanks for the friendly bump.

Last night I set up some auto test-tube fertilizing for my 135gal garage tank. Took two 6ml and one 3ml oral syringe (N & K and the smaller one for P), filled them with the powders, ziptie around them, and through a suction cup to stick them to the glass.

Just need to monitor a few weeks the rate in which the various powders dissolve. This must be the simplest way to automate fert dosing.

[billb]

Is there a good thread that discusses best ways to make stable solutions for autodosing? I have heard that people add HCl to the micronutrients to keep things from growing in the bottles and/or provide stability to the chelated iron? Is there any need to add a stabilizer to the NPK solution?


Thanks for your help

Bill

[plantbrain]

Excel works also in place of HCL.

Regards,
Tom Barr

[Wasserpest]

Bill, there is a bit of discussion at the water pump thread.

I tried Excel, but didn't notice a difference. Possible that the concentration needed to be higher. Omitting KH2PO4 from the NPK mix really helped to prevent the smell that otherwise developed.