Indigo's Fertilizer Autodosing System (56K)

[imeridian]

Well, I'll leave that in your capable hands to figure out how to make it all work for our purposes... I'd seen those timers before, but didn't realize just how they worked. I don't suppose there's much difference between it triggering a solenoid and having it trigger a relay.


I did some testing of the pumps tonight, and it appears that regardless of which grasslin timer it is pugged into, the SP200 15ml/min pump has a very high likelihood of resetting every timer whenever it clicks on or off. It seems there's some sort of surge, as it is also clicking my heater on/off. This does not seem to be the case if the SP200 pump is plugged into a Coralife digital power strip. Hopefully that'll solve the problem in practice. I suspect I'll just bite the bullet and buy that AC Jr.

[Sponsors]

[AndrewH]

First off, please forgive my lack of knowledge when it comes to ferts. Up until now I've been growing easy, low light, no fuss plants and avoiding the whole "ferts" subject as much as possible though I have read some of the theories behind dosing ferts (and agree with them).

The system looks really well designed and I can tell a lot of thought went into each detail, but I have a few questions.

1. Why are you dosing so slowly? Why not just shoot all of the ferts in one shot? Is it to help evenly distribute the chemicals or for exact dosing?

2. If you're dosing everything daily, why not have one solution with the micros and macros together?

3a. What about having the dosing system in the canopy? That way you're just letting gravity move the liquid and all you're doing is opening and closing the line (with a solenoid), basically eliminating the $80 pumps? You would need a control nozzle to only allow X amount to flow at a time, then use a timer to control the solenoid opening and closing, but that would get the job done without having to use a pricy pump, right?

3b. Or even use a really slow drip nozzle so the ferts are falling into the tank 24/7 (no solenoid needed). Figure out the amount you need each day, find a drip nozzle that will equal that amount over a 24 hour period and let it run all of the time. Simply keep a second bottle of micros and macros ready to go for when the ones on the tank run dry and change 'em out.

4. What about adding a couple of ports to the inlet side of the canister's hose? This would allow the canister's inlet negative pressure to draw in the ferts. Simply have the fert hose controlled by a solenoid and a timer.

[gmccreedy]

1. Why are you dosing so slowly? Why not just shoot all of the ferts in one shot? Is it to help evenly distribute the chemicals or for exact dosing?

This is the way the pumps work. They are not speed regulated, they are set to deliver a preset volume per time, so they are extremely accurate.

2. If you're dosing everything daily, why not have one solution with the micros and macros together?

I believe there is some voltility in doing this, but I can't quite recall the exact reasoning... Indiboi?

3a. What about having the dosing system in the canopy? That way you're just letting gravity move the liquid and all you're doing is opening and closing the line (with a solenoid), basically eliminating the $80 pumps? You would need a control nozzle to only allow X amount to flow at a time, then use a timer to control the solenoid opening and closing, but that would get the job done without having to use a pricy pump, right?

Why put something in the canopy when you can plumb it into the stand? This is a matter of preference, but I like having as much equipment as possible in the stand and I think Indiboi has the same line of reasoning. $80 for a pump isn't so bad, its solid equipment and reliable.

3b. Or even use a really slow drip nozzle so the ferts are falling into the tank 24/7 (no solenoid needed). Figure out the amount you need each day, find a drip nozzle that will equal that amount over a 24 hour period and let it run all of the time. Simply keep a second bottle of micros and macros ready to go for when the ones on the tank run dry and change 'em out.

I guess this is possible, but there is some chance of clogging since the drip would be so slow.

4. What about adding a couple of ports to the inlet side of the canister's hose? This would allow the canister's inlet negative pressure to draw in the ferts. Simply have the fert hose controlled by a solenoid and a timer.

This is basically what he is doing, but its on the outlet of the pump. Letting the pump draw it in will have some back pressure on the line, thats why the pump selection is critical.

[Wasserpest]

You can't mix macros and micros because the phosphate reacts with the iron, resulting in a shower of FePO4 which makes both nutrients unavailable to plants.

You could leave the K2PO4 out of the macros and then mix them. I found it is better not to mix them anyway as there is always a chance for some reaction and settling of the mixture.

Having the fertilizer reservoir in the canopy sounds like a more complex solution, besides most canopies are heavy enough. Solenoids aren't exactly cheap either... And connecting this to the inlet of the filter sounds like a good idea until it sucks air for some reason.

I found that with the APT pumps there is a little bit of flow even if the pump is not running. Putting them on the filter outlet allows to use a simple check valve to prevent backflow. On the inlet that would be difficult to solve.

[imeridian]

gmccreedy and Wasserpest, thank you, you gave basically the same answers that I would have.

I chose this method of dosing as I found it to be the most elegant solution to the problem. It costs what it costs. There are many ways to do it for less, and even a few where it'll cost even more.

[Johnnnn_h]

Thank you for posting pics and info!!
I picked up a pair of 1ml per min APT peristaltic pumps, & needed to find info on hoses and checks.

[imeridian]

I'm glad my post has been helpful for you.

[fishscale]

Man, I am so jealous right now. Those pumps are pretty expensive, though. Like 65 bucks each?

[imeridian]

I wrote out $80, but that was a bit of an over-estimation. $65 is correct, add another dollar or so for an extension cord & wire nuts (or pay $6 for them to put the plug on).

[Wasserpest]

Plus shipping of course. And a long time of waiting...

Just a word of warning... I bought two of those pumps, and the 15rpm one kept stripping the little plastic rotor. Not sure why. Got some replacement rotors, which stripped after a while too. After half a year on and off I ended up getting a replacement pump which works for now.

[imeridian]

Don't know if the one you were having problems with is the SP200 or SP100, but I wouldn't recommend the SP200 series, since it has mostly plastic pieces. The SP100 is mostly metal, so it should be more durable. It seems APT is one of those companies that you need to nag a little once you've placed an order. About a week after I ordered I hadn't received word of it being shipped, emailed, and then they were shipped that day (without any response to the email).

As a follow up, my timer resetting problem was indeed resolved by putting the SP200 pump on the Coralife digital timer/power strip, but still using the Grasslin for the two SP100 pumps. I had only recently put the SP200 onto a Grasslin timer, and apparently they're just not compatible.

[original kuhli]

Have you had any precipitation in either of your fert reservoirs? Do you think mixers are necessary?

[imeridian]

I haven't had any precipitation in the reservoirs, the solution is basically the same that I'd used before the pumps. As long as one keeps the mixture within the range of solubility at room temperature it should be fine. Now, mixers are indeed important if one is dosing something like a GH slurry.

The only weird thing I've noticed is that the color of Methylene blue seems to settle toward the bottom, I don't really think it's necessary so I'm not going to include it in my next mix. This may be an artifact of my recent addition of extra K, which brings the whole mixture close to the solubility limit. I'll probably drop the extra K too. It was a bit of a questionable thing to do anyway, since I didn't increase the water volume.