Poor Mans Auto-Dosing

[scolley]

If you have a LOT of timers... then this is a pretty awesome and cost effective little tool. The company selling it is too goofy for words, with all their obnoxious advertising. But if you can get beyond that, you lay down $50 for a some PC software that lets you set up as many, wickedly sophisticated, timers that you want. You then download the timers into a little module through your PC's USB port. You plug that into the wall and it executes all the multiple timers you've set up. But the catch is that you have to have purchased an X10 lamp or appliance module for each thing you are controlling. The little x10 modules cost from $5 (Internet sales) to $14 (radio shack), depending on where you get them.

But it works great. I've got timers on my CO2, UV, 4 different banks of lights, an air pump, a valve that drains my tank, and a pump that fills it, and lots more.

It's worth a look if you've got lots of timers IMO.

[magicmagni]

Wow that is too cool! Endless possibilities there!

[vidiots]

Originally Posted by scolley

If you have a LOT of timers... then this is a pretty awesome and cost effective little tool. The company selling it is too goofy for words, with all their obnoxious advertising. But if you can get beyond that, you lay down $50 for a some PC software that lets you set up as many, wickedly sophisticated, timers that you want. You then download the timers into a little module through your PC's USB port. You plug that into the wall and it executes all the multiple timers you've set up. But the catch is that you have to have purchased an X10 lamp or appliance module for each thing you are controlling. The little x10 modules cost from $5 (Internet sales) to $14 (radio shack), depending on where you get them.

But it works great. I've got timers on my CO2, UV, 4 different banks of lights, an air pump, a valve that drains my tank, and a pump that fills it, and lots more.

It's worth a look if you've got lots of timers IMO.

I'm also looking into the filters for the X10 modules, so that they will work with my lights. I really like the ones I bought from radio shack. They work with everything but the ballast for my large metal halide lamps, maybe the filters will fix that.

[scolley]

My apologies magicmagni, if this is a hi-jack. I'm sure you do not want this to turn into an X10 thread! But before everyone gets too excited, I need to add in a few caveats about using X10 for scheduling events.

1) You have to be able to accept failure - X10 signals are sent through your house electrical wiring. There can be interference (there are ways to mitigate this), signal degradation, or even power failure that causes an event signal to not be received by the X10 module. For example, it you turn a light on, and then lose power 8 hours later when the "turn light off" signal was supposed to be sent, when the power comes back the light will just remain on until the next scheduled "light off" signal.

2) You have to prepare for spurious signals - X10 rarely has a false alarm, but power surges and/or someone turning on/off the controlled device will trigger a "Turn on" signal for that device. For example, a light could be properly turned off by the X10 module (the light itself is switched on, but the in-line X10 module is letting no power through). But you flip the light switch off than on and the X10 module will actually turn the light on (thinking you wanted it on)! This can also be caused by a power surge.

This only happens to X10 modules with "local control" logic, like the Radio Shack modules. You can buy different modules, or disable it (as I do) using these instructions.

X10 is nice, but it's not perfect. I have autodosing, but I do not control it with X10 modules at the moment, because I cannot afford the possibility of losing power during dosing and the "dosing off" signal not happening and over dosing the tank when power returns. I haven't tested that yet.

Technically the control module I pointed out in my prior post has battery backup. So it should be able to turn X10 modules off when you have a power failure. I just haven't shut the power off at my house's fuse box to test it.

So maybe should not have brought it up in a dosing thread. Sorry. I was inappropriately responding to the "needing a lot of timers" comments. It is not appropriate for dosing timers IMO. A temporary power outage causing your lights to stay on all day is one thing, dosing for 24 hours is something else entirely.

[vidiots]

Since there were some questions about my questimate as to how much the fluid head level effected the flow rate and my figuring of more head height being better, I desided to put my thoughts to the test.

I used a gravity feed drip system to conduct the test. First I mounted the reservoir 5.5" above my sump and adjusted the drip rate which remained at the same setting for the remainder of the tests. I measured the drip rate using a stop watch in drips per minute, with the reservoir low on fluid and again with the reservoir full of fluid. A change in fluid level in the reservoir bottle of about 4 inches.

Second I mounted the bottle at a height of 29 inches above my sump and repeated the above test.

The results suprised me a little. Instead of there being a 1:1 corelation between a percent change in head height to percent change in flow rate the corelation was about 1:2. This means that a 10% decrease in Height above the sump decreased the flow rate by about 20%. However I was dead on with the asumption that having the bottle mounted higher results in a much smaller difference in the empty versus full flow rate.

I have desided with these results that I am going to keep my bottle at the 29" height. The % change in flow rate at this height is about 25% Empty versus full reservoir. I figure I will just measure the two after setting it, and average them and should be able to keep my dose rate constant to within ±12.5%.

If I were to keep my bottle at the 5.5" height my dose rate would vary by ±30% of the average.

Hope this information is useful to those designing their own auto dosers.

[kimo]

Originally Posted by vidiots

With the air powered dosing pumps you can't get a pressure buildup in the bottle because you have a leak designed into the system. That leak is where the fluid comes out. The maxium pressure you can get above atmospheric with the pump off is equal to the head height of the output hose, which only changes with the fluid level in the bottle from one dose to the next unless you move the bottle or hose. If the pressure in the bottle were to exceed atmospheric pressure plus head height, fluid would flow.

What you do have increasing from one dose to the next is the volume that the pump has to fill with the pressurized air. Remember the pump is pumping air at a relatively consistant volume per minute. You use a timer to make sure your timing is consistant. At the start if you only have one cubic inch of air at the top of the bottle, then use the pump to add another cubic inch of air you have doubled the pressure inside the bottle which causes fluid to flow at a good speed. Now after several doses you have 10 cubic inches of air at the top. It now takes the pump 10 times as long to pump the bottle up to the same pressure/flow rate. What you tend to end up with is a time delay before fluid flows after the pump comes on, a slower flow rate as the bottle empties, but it also continues flowing for a longer time after the pump shuts off as this larger volume of air at a lower pressure equalizes with atmospheric. This is eventhough you have the timer on for a fixed amount of time.

As I was saying more head height on the output hose, a large diameter container, and a stronger pump should minimize these effects.

If you could find a thick walled balloon of the proper size to fit in the bottle (those kid's balloons lose too much air due to leakage), then the balloon would expand as the fluid was used, keeping pressure (and volume) in the bottle the same, and fluid delivery the same over the whole dosing period.

[CardBoardBoxProcessor]

Well... does this system work? I though of doing the same thing.. my question is.. how do i mix the ferts in? how do i know it gets the right does? see how much water comes out in 1 minute and for every ammont of that i add the needed dose for that day?

[CardBoardBoxProcessor]

oh.. the whole presure thing.. you would need a container of water with a back stop valve that leads into a bladder inside the container that is being presurized. thus.. the new space is filled and it is not diluting the solution.

[magicmagni]

Originally Posted by CardBoardBoxProcessor

Well... does this system work? I though of doing the same thing.. my question is.. how do i mix the ferts in? how do i know it gets the right does? see how much water comes out in 1 minute and for every ammont of that i add the needed dose for that day?

Very simply. Just decide how much water (size container) you want to work with. I'd say go with as large as a container as you can.

Take what you would normally dose in one week or two weeks or 3 weeks (however long that you want it to last for) and put it into the dosing container. Time it out with the timer so that it empties the contents over the amount of time you want. You can fine tune it with the amount of water you add to the container. Does it empty too fast? Add more water. Too slow add less. You can also play around with the time the timer leaves the pump on for. Try 1 mintue instead of 2 for example if it's going too fast.

Use plain water at first untill you get dialed in. Then add the ferts once you know it's working correctly.

Ferts may settle a bit in the containers. This can be countered by putting an airstone in the container. This will mix up the solution everyday a bit. Oxidation should be minimal since it's only on for a minute or two max.