Poor Mans Auto-Dosing

[vidiots]

Originally Posted by Wasserpest

I believe what Sietch experiences has nothing to do with increasing head pressure. The little humming pumps shouldn't be bothered by a few inches of head.
I think it is one out of two possibilities.
My bet is that somehow the gallon container is getting pressurized. This needs to be prevented. Air compresses, and the emptier the bottle gets, the more it will compress and as result you get less and less solution into the tank.
Make sure that the airline that transports the solution from the bottle to the aquarium is not restricted in any way. It should be open on the end, no nozzles or such which block the flow.
Another possibility would be an airleak at the cap. That would make a big difference for the ability to push the liquid out of a full or empty bottle.
Just my experiences...

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.

[Wasserpest]

You are right. I was thinking more along the lines of my 20oz Gatorate bottles, but I guess in a gallon things might need more time to pressurize.

Still, restriction on the output, or simple air leak, will make things worse.

[magicmagni]

That's a great explaination vidiots. BTW have you tried a differenct container yet? I have had good luck with some glass wine jugs that I had around. I believe they are 4L size. I have one for macros and one for micros. I like having the large reserve of liquid as it works as a auto top off as well and give me a lot of wiggle room to fine tune the level. If it empties a little too soon I fill it up a bit more. Not soon enough, I fill up a bit less. The delviery rate is pretty consisent too.

I just thought of something that may also contribute to the inconsistant doses. The Plastic bottle. Like you say once atmospheric pressure is exceeded the fluid flows out of the tube. This slight pressure buildup may be enough to "ballon" the plastic bottle just enough to cause issues -they are really flexible. Instead of the plastic bottle a glass one would be better as there is no chance of compression and expanson to influence dosing volume.

[kzr750r1]

Originally Posted by magicmagni

That's a great explaination vidiots. BTW have you tried a differenct container yet? I have had good luck with some glass wine jugs that I had around. I believe they are 4L size. I have one for macros and one for micros. I like having the large reserve of liquid as it works as a auto top off as well and give me a lot of wiggle room to fine tune the level. If it empties a little too soon I fill it up a bit more. Not soon enough, I fill up a bit less. The delviery rate is pretty consisent too.

I just thought of something that may also contribute to the inconsistant doses. The Plastic bottle. Like you say once atmospheric pressure is exceeded the fluid flows out of the tube. This slight pressure buildup may be enough to "ballon" the plastic bottle just enough to cause issues -they are really flexible. Instead of the plastic bottle a glass one would be better as there is no chance of compression and expanson to influence dosing volume.

The only thing I'd worry about with glass is exploding.

Takes me back to the third of July a while back like 1982 or so.

Three kids find an empty gallon wine bottle with the cap. Three kids decide it's a great idea to place a lit spinning flower fire work inside the bottle and spin the cap back on.

Now to this day will not know if it was temp or pressure or both that made the bottle explode but it was impressive... At the middle of the burn I ( yeah ) told the other two to turn away. Pop. Little brother had a little shrapnel in his leg and that was all. We were lucky to say the least.

Sorry for the flash back but it's the 4th and my dog is freaking out. We live next door to the largest park in town and everyone is out setting off there works.

At some point having some expansion to deal with will be better served encasing a container in a foam brick. Depending on the size making a cardboard form to place the containers in and spray in the foam. It will expand around the containers and in the same swoop insulate and keep the light from the solutions.

I'll have to try this with 2 liter bottles... See what happens. Since there are two bottles of pop here at the house today it's time to try this method. I'm going to the garage and find the air pump.

[magicmagni]

Well we are not putting fireworks in the glass here LOL. This is only air and likely not more then 10psi if that. Most glass beverage bottles are pretty thick so they don't break in shipping. I think you would have to have about 100psi or more on there before there is a chance of anything happening and even then I think the hose connection that you glue on the cap would pop off before the glass did anything.

I you are very paranoid though you could go ahead and take some packaging tape and wrap the whole bottle with it. This way here if it breaks it will contain the glass- sort of like the windshield on your car. I can say I have run this system for a very long time now and never had a problem or even a hint of one in this regard.

[crazie.eddie]

What's the brand/model of the 1 minute digital timer you bought? I've been looking around for similar timers and all I can find are cooking timers.

[vidiots]

Originally Posted by crazie.eddie

What's the brand/model of the 1 minute digital timer you bought? I've been looking around for similar timers and all I can find are cooking timers.

I bought the Radio Shack Home Automation Starter Kit for around $40. It came with a digital timer that be programmed and can controll up to 8 devices. It has remote modules that the devices plug into. The timer/controller is battery powered but plugs into the wall to send signals through the power circuit to the modules. The timer and all the modules have to be plugged into the same electrical circuit to work. It worked beautifully for everything except one. That was the large external balast for my three 175watt Metal Halide lamps. The balast generates too much electrical noise for the modules to be able to receive the signals from the controller correctly while the lights are on. To work around this I put the lights on a mechanical timer, and scheduled all the other devices to switch on and off while the lights are off. By the way the system works great for regular flourencent aquarium lights even the lamp module which is not supposed to work well with flourescent lighting.

[vidiots]

Originally Posted by kzr750r1

The only thing I'd worry about with glass is exploding.

I agree that it would take a lot more pressure to break a wine bottle than the average aquarium air pump can generate. These bottles are designed to hold a lot of pressure generated by the yeast CO2 caused by the wine fermenting inside, and would probably be ideal for DIY yeast CO2 generators. Your air line tubing would burst or come appart long before those bottles ever did.

[kzr750r1]

Yeah Yeah Yeah..,.. I understand it's only 10 PSI or less and it can go higher without an issue. This just brought up a bad memory... It was the 4th.

The top would probably leak before it burst even at 100 psi, but I’m not going to experiment to that point.

My life is full of past mistakes. I’ve had go cart rims explode on me not knowing that the air hose had 150 PSI on tap. Lucky to still have my left thumb after that one, say it with me, PAIN. We all learn from mistakes and keep mental notes not to repeat. Cross reference pain (mental or physical) and recall something that could save others the same. All I was trying to convey. Just be careful. K.

[magicmagni]

Just keep living to tell!

On the timer. This is the one I use. Has battery backup so you never have to reprogram it after a power outage.

http://www.rewci.com/insedaydiprt.html

[vidiots]

Originally Posted by magicmagni

Just keep living to tell!
On the timer. This is the one I use. Has battery backup so you never have to reprogram it after a power outage.

http://www.rewci.com/insedaydiprt.html

What do you think of that timer? I've considered getting some of those. The part that stopped me is that I'd need like 7 of them and at $23 each that adds up quick. The only other think I don't care for looking at the picture is the amount of outlet space it takes up.

Ideally what I'd like to someday find is a power strip where all of the outlets could be independantly controlled by a single built in programable digital timer similar to the one you have.

I know that coralife makes a digital power strip, but the outlets are not all completely independant.

That way everything could be controlled by one device, lights, water changer, auto doser, CO2 solenoid, etc.

[magicmagni]

It gets the job done. If I did it again I would have used them for all my timing needs on my tanks. What would be really nice for this application (as far as really fine tuning easier) would be a timer that you can set by the second and not the minute, but it's all good.

As far as outlet space what you can do is get a short extension cord, like say 1 foot and plug the timer into that.

Wow why do you need so many timers? Do you have that many planted tanks?

[kzr750r1]

It is a good unit with a lot of flexibility, nice to not have to re set each power outage... The plug placement is problematic but can be overcome with some handy work or trick side mounted receptacles on a power strip. Making pig tails is simple too. Just make mini extension cords from your power strip.

[vidiots]

Originally Posted by magicmagni

It gets the job done. If I did it again I would have used them for all my timing needs on my tanks. What would be really nice for this application (as far as really fine tuning easier) would be a timer that you can set by the second and not the minute, but it's all good.

As far as outlet space what you can do is get a short extension cord, like say 1 foot and plug the timer into that.

Wow why do you need so many timers? Do you have that many planted tanks?

I too would like to see timers that can be set in seconds.

I've had to do the extension cord thing for a few things too. Just looks neater without them.

Actually I only have 3 tanks with plants in them. My light fixture over my 180gal tank has 4 seperate power cords for independant control of the lighting. I currently have all 4 pluged into a power strip that is pluged into a timer. I'd like to have them on seperate timers so that I can stagger the lighting thru the day and do the sunrise/sunset effect. I was also thinking of adding some moon lights which would require another timer.

The automatic water changer on my 180gal tank is on a timer. I'd also like to put my CO2 controller on a timer that shuts the CO2 off at night, to save on CO2 refills.

I'm still working on an auto doser that I am completely happy with, and if I use an air or liquid pump that will need yet another timer. I want good consistancy and high reliability with my auto doser. The liquid pump method shows promise especially if I use a large reservoir. I'm also gonna test the gravity feed drip method, thinking simpler might be cheaper and more reliable with fewer things to go wrong.

I'm not to concerned with timers for the other two small tanks, just to turn the lights on and off for them. They are not really display tanks, just a place to temporarily store the excess plant clippings and fish fry until I deside what to do with them.

[magicmagni]

Yeah I use a lot of timers too. I have 3 banks of lights on the 120gallon that come on in stages via the 3 timers, then the timer for the doser.

There's probably something out there that will control everything for you, but if probably costs a lot.