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IUnknown 11-09-2004 11:18 PM

DIY Automated dosing/topoff
I'm planning to finally order this stuff. Here is the journal that I've written up,

For under $100, you can put together an automated dosing or evaporated water top off system. The system I designed allows me to dose 1mL up to 14mL of fertilizer, into my canister filter line, any day of the week. For a top off system, measure your average evaporation and determine how much R/O water to add using the SP100 cut sheet. I use a simple digital timer, the DT17 (available at HD), to dose (minimum of one minute). The SP100 Peristaltic Pump is available from I selected the 15 RPM motor that uses 1/16" ID Norprene tubing to dose .9 mL per minute. I could have used silicone to get closer to 1 mL per minute but I was worried about back pressure in my canister filter. I've added a check valve and TEE to feed the fertilizer directly into my canister. The following is a list of adapters that I got from You can also simply dose the fertilizer straight into the tank.

1/16" tubing neoprene 2'
1/8" tubing neoprene 2'
1/4" tubing neoprene 2'
0706-103 1/8"x1/16" reducing connector
0706-153 1/4"x1/8" reducing connector
5111-0-03 PP tubing check valve 1/4"
0715T-050 1/4"x1/4"x1/2" polyethylene TEE

scolley 11-10-2004 12:53 AM

I spent too much
I don't have it all in yet, the pump arrives Friday, but I clearly just spent too much money trying to do something similar. But getting the timer at Radio Shack, and the peristalic pump and a custom T from was definately past $100. I feel a bit stupid now.

Can you explain the back pressure concerns on your canister?

And not to harp on a recent subject, but are you planning on putting the T pre, or post canister? And I haven't even stopped to consider questions like how this relatively high concentration of cold fert will affect an in-line heater or CO2 reactor. Gosh, it's all connected.

I can't wait to hear how it turns out - 'cuz I'm trying to figure it out as I go...

IUnknown 11-10-2004 04:39 AM

Sorry I didn't informed you earlier, you definitely saved me some money. I have back pressure on the Co2 tubing that connects to the reactor. I think its because the glass outlet pipe probably restricts the flow. I'm planning to install the TEE on the intake side (no room left on the outlet side) so I guess there would be no pressure problems. I don't think it really matters either way. I dose so little on my 20 gallon, I don't think it matter where I install the TEE.

scolley 11-10-2004 11:28 AM

The intake side has got to be free of most complications, but there still can be pressure to recon with. I have assumed that there is not enough pressure to worry about, but the check valve from is great! I didn't know where to get a fluid check valve. Looks like a great site! So I may have overpaid for a T that doubles as a check valve, but I'll save money in the future on liguid flow problems using them as a source. Thanks.

All that said, if someone is willing to try it, I'll wager that a peristalic put deals well with the back pressure issue, and will not flow in reverse because of it. I guess the real danger is just something happening to your setup, and draining your tank. Check valve sounds like a necessity, not for pressure, but for safety.

IUnknown 11-10-2004 03:38 PM


Check valve sounds like a necessity, not for pressure, but for safety.
I was also thinking the check valve was needed to keep the fertilizer from being sucked out.

scolley 11-10-2004 04:01 PM

Pls excuse my ignorance. I know the check valve, in the direction you've documented it, will keep water from flowing our of the line if something happens to your dosing setup. But can it also keep fluid from being sucked out of the fert lines?

I did't know a check valve could do that. And even if it won't, the peristolic pump should act like a shut off valve when it is not moving, and not allow anything to flow thru it. In either direction.

IUnknown 11-10-2004 04:33 PM

I was thinking more about keeping the fertilizer from mixing with the aquarium water. Yeah your right the pump will keep the fluid from flowing, but I figured there had to be some kind of wall to keep from the solutions from mixing. Maybe that wouldn't work?

scolley 11-10-2004 06:00 PM

If we assume the pump will keep the fert out of the water line (sounds like untested agreement on that point), then I would definately want the valve for safety - not finding the tank siphoned off onto the floor.

But it does raise the question of "at what point do you want to separate the fert from the water - keeping it from mixing?" That can be either at the pump, or at a check valve (if used).

Since a "dose" is anything that has left the pump, I would assume thar you would want everything that has left the pump to be in the water. Even if that last bit left in the feed line to the T just seeps in after the pump stops, rather than coming in under pressure. It's still part of the dose.

But to do that you have to eliminate the check valve, raising the safety issue again.

This is a quandry.

scolley 11-16-2004 06:33 PM

My peristalic arrived Friday, a few days ago - spent much time this weekend getting it hooked up. First challenge - verify flow rate. Based on my measures, rather than the vendors posted .5ml/min, it is closer to around .63 +/- .02ml/min.

Learned a few vauable lessons worth passing along...
1) If you get a pump with 1/32" tubing, finding reducing connectors will be hard, and possibly very expensive. Everything appears to get much easier with 1/16" tubing. I had to kludge it with using silicon air tubing as a coupling to larger hose sizes, augmented with super-glue at the point of contact, reinforced with liberal amounts of silicon sealant at the seams.
Lesson - 1/32" tubing does not have readily avilable reducting connectors.

2) 1/32" tubing has an advantageous flip-side - very, very slow water flow. In my case it eliminated the need for a check valve, and the problems that introduced. Sure, I could lose my whole tank. But at the flow rate the tubing accomodates, I figure it would take quite a quite a few weeks!
Lesson - 1/32" tubing can reduce the requirment for a check valve.

I'm sure there will be more lessons still as I try to get the tank settled on a "constant" supply of nutrients, rather than the ups and downs of every other day or so.

IUnknown 11-23-2004 05:32 PM

I put my auto dosing equipment together last weekend,

Ibn 11-23-2004 06:08 PM

Wow, looks good. Might have to try that out myself as a DIY (have an itch towards DIY lately, not sure why). Mind sharing how much the total cost was and amount of time spent piecing it together?

That second shot looks like the bottom of my stand. I've got my light plugged into two of those timers right now.

scolley 11-23-2004 06:14 PM

Great stuff!

It looks like you are dosing from liquid in the Seachem bottle. Is that right? So are you dosing fairly low liguid volumes? Like 5-20 ml/day?

And if so, what's the flow rate on your pump? - I'm assuming your timer works in increments of minutes.

IUnknown 11-23-2004 10:49 PM

SP100 OEM Fixed Flow Peristaltic $57.00
TubingMaterial: 1G - Norprene, General Purpose $2.00
TubingSize: 016 - 1.6mm(1/16")
TBG023.003 1/16" Norprene $7.00/pk of 10ft
TBG023.007 1/8" Norprene $7.00/pk of 10ft.
TBG023.017 1/4" Norprene $8.00/pk of 10ft
$24 for the timer
$5 for tubing reducers and check valve
You can get clear 1/4 tubing at a hardware store, just as much as you need (better so you can see if the fertilizer has run out). I couldn't find the 1/16 and 1/8 so I had to buy 10 ft worth.

I dose 4mL of flourish every other day.
Flow rate is 1ml per minute. Timer has a min. of 1 minute.

bharada 06-03-2005 08:15 PM

Resurrecting a thread rather starting a new one,
With a three week vacation coming up in August I've decided to jump full in to the auto dosing wagon. After looking at the gravity fed solutions and reading about the inconsistancies in their dosing rates I've decided to go motorized.

I ordered six of the dosing pumps (one each for macros and micros for each of my three tanks). I seem to have gotten into a pretty consistent dosing routing over the past couple of months so I'll be trying to mix up batches of macros to last about a month for each tank. I'll test tank and reevaluate the mix after the month is up. So I'll have at least a month and a half to configure the system before vacation starts.

The auto feeders will arrive next week so I'm fully on my way to automating my day-to-day routines.

scolley 06-03-2005 09:21 PM

Hey Bill, that's great stuff! I love autodosing. Makes things soo easy. Welcome to the club.:proud:

With 6 pumps, you might have to be the honorary president!

Sound's like you got the aquamedics. And they may be very accurate. But I wanted to just let you know that some of these pumps (like mine) do not pump at their rated flows. I believe mine pumps about 25% slower than its rated flow. So you might want to measure it first to confirm the flow rate before you calculate your schedule.

If you'll be dosing everyday, you've got to deal with the "target vs. average" question, and decide what level you want to hit on your ferts. While with a typical dosing schedule you "target" a point to hit when you dose, you go lower than that in between doses. Daily doses allow you to peg a spot and hold it. But the spot you select might not be the same as your old "target".

Good luck! And keep us posted of progress please.

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