Poor Mans Auto-Dosing

[shalu]

Bill, I got the dosing pump but have not set it up yet. I intend to use it for macros, mix NPK. I use two Eheim liquidosers(got one of them really cheap from Ebay) for trace/micros right now.

The air pump idea is really interesting, I might try it on one of my tanks. The only problem is, none of the air pumps I used so far is really quiet.

[bharada]

I'm getting some side cash for a freelance jog I did a whlle ago so I just went ahead and ordered the six pumps and some tubing. If it were strictly for day-to-day dosing I might be more inclined to try a less expensice alternative. But with the long vacation looming at the end of summer, I'd rather spend the money and get the added control offered by the pumps.

The Eheim liqiudoser would be nice, but the pumps will allow me to auto top off, too. I'm figuring that the 40 will lose about six gallons of water due to evaporation. The 125 will be more like 12 gallons lost. During my vacation I can mix my macros up in one 5 gallon bucket (suitably diluted) and micros in another.

My 20 will be the only one that the luiqidoser would've worked on since it's close topped with minimal evaporation, but this way I'll have a consistent setup throughout the house.

[g8wayg8r]

Finally, I have a use for that old air pump in the basement.

I love this method and would use it over the gravity feed any day. That method depends on the head from the height of the solution in the container and it will vary greatly unless you have a reservoir like some of the ultrasonic humidifiers that keep a constant water level. That's way more complicated that the air pump method. Since the head for the air pump method is determined mostly by the run length of the tube from the bottle below the tank to the rim of the tank, the amount of ferts or water in the bottle is almost irrelevant. The dose rate should be relatively constant.

Simple, inexpensive and effective. Gotta do it.

[scolley]

Just wanted to jump in... been watching quietly. If you can make this clever solution work magicmagni, you'll have done the community a great service!

I'm looking forward to seeing how this works out long term!

[magicmagni]

Thanks for jumping in Scolley. Well I've taken so much from this site that I didn't even think twice to contribute this post when I thought this up. I mean heck if everyone didn't share their ideas we wouldn't have all of these plant specific gadgets we all use to make our lives easier. -DIY reactors and Yeast CO2 to name a few.

This is a feasible alternative to whatever else if out there. Just note that this method is to daily fert dosing as DIY CO2 is to injecting C02. It is in the ballpark, but not exact. I think I need to make that clear. Also note that the small air pump laying around from your 10 gal isn't going to cut it on that 100 gallon. What I use is a Tetra tec pump that was rated for 100 gallon tanks if I remember correctly. I can look up the exact model if anyone is interested, but it's the one with the green dials on the sides and two outputs

Update: I was cleaning the Garage- well actually looking for something else and I found a clippord needle valve from one of my Co2 rigs of several years ago. One end is barbed and the other is threaded. I went ahead and swapped out the cheap plastic air valve for this and I like it much better. It's easier now to adjust. The barbed end is connected to the supply and the threaded side has a short piece of airline that that I was able to slide over threads. This side directs the drops into the tank a little better. Note that the hose is still suspended above the water so that I can see the drop rate.

The only downside I note with this system is that when starting a new fert solution you have to open the valve all the way up so that you can "prime the line." Then when all the air is out and you have a good flow you can taper down the flow with the valve to get the drip rate you want. So there is a bit of tinkering, but its an extra 5 minutes and then I'm set for the whole week although I must admit I'm spying on the drip rate whenever I feed the fish just to make sure. While it's not perfect I can usually set it so that the container empties into the tank in about 6 days give or take 4-6 hours. One can also experiment with the starting solution size to further fine tune it. More solution=longer time to finish, Smaller solution= less time to finish. I must note again for anyone trying this to use plain water to experiment until you get the hang of it.

[magicmagni]

Heres another update. I was having some problems with the hose extension that I had comming off the needle vavle. It seemed to be throwing off the drip rate so I removed it and modified a bit.

Here's a pic of how it is now. I used a paper clip as a sort of holder for the vavle and attached it to the filter pipes. It is alligned with the cutout in the hood of the tank.

[magicmagni]

Here's another update on the airdoser. I actually got it working pretty good, but it took some time. I actually stopped using the needle valve as it was getting clogged too easily. I went back to original standard plastic valve. Another thing that I did too was swap out the original Sobe bottle for a 2L bottle. I did this because I wanted a faster drip rate. It seems that a drip rate of 1 every 3 to 10 seconds works better and is more consistent rate for the plastic valve.

[scolley]

These honest, long term use reports are what makes this a good thread IMO. It's one thing to say "I built it" and it's another, far more valuable thing to say "I built it, have improved it, and am still using it."

If you are having trouble with the flow, have you looked at other method to control the flow? Aquatic Eco-Systems seems to have a good selection of valves.

[magicmagni]

Thanks!! I forgot about that website. A lot of possibilities. Feel like a kid in a candy store!! Although another idea crossed my mind: get rid of the valve all together!!! Am I losing my mind? Maybe, but I'm starting to see deficiencies in my plants even though I am adding the same amount of ferts weekly that I was adding before. The only change I can think of is that before the plants were getting a dose all at once ie. I dumped several capfulls of Flourish and Flourish Iron at a time a few times a week- giving surges of nutrients. Whereas with the doser it's getting a small amount at a time. For some reason it seems to me my plants prefer the former.

I wonder what others who are using other dosing systems would say to that? Perhaps this is not an issue with their setups because it does not constantly administer the dose, but rather shoot a day or two worth of ferts in the tank when the timer goes off? I'm thinking I may want to adapt that method of administering the dose with the airdoser. So instead of using a valve just put the airpump on a timer to go off for X amount of time every few days. I think they have programmable ones that can do that?

[scolley]

You can get a programmable timer ($20-$40) to do that. But I really have a hard time accepting the proposition that it matters. In fact, I have a hard time believing there is any difference between dosing every other day, and dosing daily.

Think about it. Let's say you target Nitrates to 14ppm. On a given day you dose so that it is right on 14ppm. Then two days later, it's fallen to 11 ppm, and you dose it right back to 14ppm. I cannot buy the concept that the swing back and forth between 14 and 11 matters to your plants. Both are enough, and not that far apart.

IMO you are barking up the wrong tree. If you see improvements when you dose manually, I think you have problems with your auto dosing amounts. Only rigorous testing and record keeping will answer this question for you.

[magicmagni]

You know I think you got a point there. I went back through my logs and sure enough I was dosing more traces when I was dosing manually before using the doser. For some reason I stepped it back, probably just need to up the dosage back to what it was before.

[scolley]

Yeah, I think that an unexpected drawback to autodosing, no matter how you accomplish it, is that you have to have records. You've got to know how much of what you are putting in your dosing reservoir, and at what intervals. Since you can't be certain of how much is going in (at least for DIY rigs), so your records are the only way to know how much is being used.

And then, on top of that, you've got to do periodic testing still. Otherwise you don't know when to change your mix, or your amounts.

Auto dosing is automated, but unfortunately not magic. It still takes work. But if you are doing it right, you should eventually be doing a lot less work, a lot less often.

[magicmagni]

Well here's another update on the system. I am still using it for micro dosing (haven't had time to mess with setting up another bottle for macros yet). I settled on what I call "the final design" because it has been in operation the longest amount of time without me fiddling with it. Here is a crude drawing of it as it is now.



Since the last time I checked in I've made a few mods:

1. Revised dosing control: I have decided to use a $15 digital timer to turn the pump on and off to control the amount dosed to the tank. Instead of restricting constant flow of fluid with valves I'm now letting the flow go unrestricted and just controlling the amount of time it goes into the tank (like you would do using a traditional dosing pump). This takes care of noise issues (don’t have to listen to the pump all day long), wear and tear issues of the air pump being on 24/7, and eliminates high pressure build up that was present on the old design. I'm currently setting the air pump to run for 2 minutes.

2. Larger reserve: The system now uses a 4L wine jug. This is the type with the screw on top. (Actually they are identical to the sobe bottle tops.) The main reason for this was because the unrestricted output (remember I removed the needle valve) more liquid could pass in a given amount of time. The shortest time interval the digital timer could do was 1 minute intervals. Probably 40 sec interval would be perfect, but I had to improvise so diluting the fertilizer in more water was the solution. Not a bad thing (think of it as a auto top off too)

3. Solution mixing: Sometimes when the trace solution sits things settle to the bottom so I decided to add an air-stone to the solution bottle. Before air just ran into the bottle above the solution level just under the cap, but now I've run a airline to the bottom with the air-stone so when the air pump goes on it agitates and mixes the solution up a bit. A concern with this is oxidation, but it is only for 2 minutes a day- I doubt that it is enough to really do anything, but mix the mixture up a bit. One thing to note is that a check valve should be used on this airline or else the mixture could siphon through the air-stone and to the pump.

This system has been in operation for the last 4 months without a single problem. Works extremely well at this point. Pretty much just refill the bottle after my water changes on Saturday and it's empty by Friday afternoon.

[magicmagni]

To recap on what is going on here. I am using air pressure generated by a standard aquarium air pump to push liquid from a bottle into the tank. The amount of fertilizer to the tank is controlled by limiting the amount of time the pump is on. This is done with a programmable digital timer that is capable of running for as little as a minute per day. The amount of liquid administered to the tank is a function of 1. how much fluid is in the fert container and 2. how long the pump runs 3. (but to a lesser degree) how much pressure the pump produces. Manipulating these three factors will yeild the desired results: dosing the proper amount of fert liquid solution per day. Some trial and error is reqiured, but not anything that can't be sorted out in an afternoon or two.

[Betowess]

That is a really interesting alternative to the peristaltic pumps. Do you know the ~ cost of that air pump? Great thread.