automatic water changer description & questions

[perle]

Yeah I am quite satisified with it. Not all the things you mention are problems, either.

For one, the RO system runs only on water-pressure. Electricity failures don't affect anything. And water pressure failures for an extended period of time are very, very unusual.

I think I see how your overflow box would work, but wouldn't it evaporate at the same rate as the tank? In which case it wouldn't help anything. Maybe I don't understand.

Edit: nevermind I figured it out. It lets you set the lower limit of the waterline of the tank much higher than the actual base of the inlet by dropping the inlet deep into the box.

Underflow is not really an issue because the outlet tube is only 3-4 inches from the surface. So in no case will it drain so much of the tank as to cause a problem for the animals.

The overflow is the problem. It could be remedied with an electric overflow monitor at the external base of the tank (since water will run down around the base), and some kind of electric valve. A neat way would be, with a default-closed valve (that is, only open when it is powered) would be to wire the valve in series with a fuse. Also, wire an overflow monitor (and really it is just a pair of wires spaced very closely to each other) in series with the fuse but powered by a stronger current so that if the circuit completes it blows the fuse. This means if your power goes out, the valve closes for the duration of the power outage, or if the tank overflows, the valve closes permanently until you replace the fuse or breaker or whatever you wanted.

The key is to avoid computer control. It's more complicated and less reliable. After all we are simulating nature here!

Yes, a basement would be ideal. Just put your tank near your basement sump and don't worry about overflow at all.

Once I am more sure that the setup is complete I need to tape over the tubes so that algae doesn't grow.

Where is that FedEx truck!!

~perle

 

[TomK2]

Tbone-

That's the part that you and I have difficulty with. Perle is saying that if the water drops below the air hole, then rises back up again, that the outflow will resume automatically.

I had thought that once the air hole was exposed to air, thus preventing further tank drainiage, then the water went back up again the outflow would not resume. So I really don't get the point of the airhole. Set the sink height to the tank level you want and forget it, as in your classic overflow setup pictured above.

However, if the sink height gets accidentally lowered, then the airhole would prevent tank level from dropping futher, but I can not see how flow would resume automatically once the level rose again.

Like you, I understand that the siphon stays intact as long as water is above the airhole.

 

[perle]

Tom: the airhole is at the exit end of the tube, over the sink. The inlet is just an inlet. The point of the airhole is to end the siphon at a point high above the sink, while still being able to direct the output through a tube down to the drain itself--to eliminate mess, that is all.

~perle

 

[TomK2]

ahhh, so you have one one continuous tube from tank to sink. I just went up and looked at your diagram, and what do you know, you have sink on left and tank on right. Duh, my western education has clearly indoctrinated me into left to right thinking only! Take a look at my posts, and imagine your system with the airhole in the tank instead of above the sink, and you can understand why I was so confused! Thanks for the patience.

So, now I totally understand! It all makes perfect sense to me. Yes, your system is essentially a classic overflow, and tank water height is regulated by the height of the airhole, which is the point where any siphon would be broken. Very cool, very sound system. As long as no air or kinks get in the tubing or your airhole height is not changed, everything should be stable. Your overflow would even adapt to changes in RO output, up to the flow capacity of the tubing. In essence, your tank is something like a pond up stream from a dam. Water from the stream (your RO unit) is constantly flowing into the pond (your tank) then exiting over the dam (your overflow tubing). I like it!

Ya know, I could do something like that too. And if the inflow was only 3 to 5 gallons a day, there wouldn't be any need to dechlorinate either. Hmmmm. Or I could just elevate my holding tank to match the aquarium height, put an overflow from my holding tank to the aquarium, then another overflow from the aquarium into a drain. Thus, my faucet output would go into the aerated holding tank for dechlorination (transit time through the holding tank would allow aeration to remove chlorine and allow the water to be heated), then overflow into the tank, with tank overflow to the drain. Instead of 20 to thirty gallon water change once or twice a week by operating the pumps, I could do 5 to 10 gals a day.

Nice set up Perle.

 

[hashbaz]

Ain't Perle's system pretty slick?

 

[Jarred Darque]

I have thought over and over about an automatic water change system.

Your system has one minor (major) problem. Now, I dont know the the power cycle of the RO unit, but I imagine that if it loses power it will stop pumping? Then your syphon will continue you drain water out of the tank until the water lvl in the tank is either a) same height as outlet of syphon, or b) same height as inlet of syphon, which even one is higher.

now, if the syphon inlet is set high in the tnak, then this does not seem like a problem, you may lose an inch or so of water. But when the water reaches this lvl, you get air in the syphon. Well, when the poewr kicks back on, the RO unit comes back online and starts pumping water. but your syphon is not taking any more water out of the tank, the tank will then overflow. and make a big mess.

There are two ways to counteract this. dont use a syphon, use an overflow. you would have to cut a hole in the glass of the tank, run a hose through it, then silicone/seal it. having the hose always pointed at a downward angle from the water inlet to the outlet.. It will no longer syphon water though, it will merely flow any water that is above the inlet of the hose.

The other way is again, using an overflow into a seperate tank, a normal sump tnak filter even. from here you run a water pump to your sink, garden, whereever, thatis run off of a float (think the float in your toilet) so that if the water lvl in the sump drops to far the pump cuts out instead of burning out tryint o pump air.

Now, in order to keep the pump from cycling on and off all the time, then you would need to use the low limit float, but also a high limit float which basically means that the water lvl has to reach a certain height in order for the pump to turn back on

you can also set an even higher high limit float that will turn the water-in pump/RO unit off in the event that the outlet pump stops working.

You would want the outlet flow to be as close to the inletflow, on the higher side though, than the inlet flow. this would prevent tank or sump overflow

And of course, if your not using a RO as your intake, but say a line tap off your house line that you still need to dechlorinate, you can add a dropline into the intake to dechlorinate water as it enters tank. If your using a large drum, which you would say, for a 20 gallon tnak where you change 5-10 gallons per week, you would only have to fill up once every few months, you just add teh dechlorinator to the drum of water, which is adventageous is you are doing this to a planted tank, as you cna add the months or two months worth of mineral/elements etc to the vat instead of having to add them daily or every other day and all.

I do plan on doing somethig like this when I get my next big tank, the upgrade from the 75. For my 75, I am simply going to keep a tank under the stand and syphon water from tank to sink and use a water pump to pump water from the tank under stand to the main tank. Then will fill up the under tank again with syphon from sink. this would give me a few days to get temperatue and pH matched to the main tank before the water goes in tehre the next water change

 

[TomK2]

I think Perle's system is essentially a thin tubed overflow. Height of water is controlled by the airhole height in the horizontal stretch of tubing over the sink. There is an airhole instead of an upturned tube as in tbone's diagram, to prevent the part of the tubing that makes the final downward journey to the sink from developing a siphon that would drain the tank to the level of the intake. I struggled with this one too, but if you think of it as an overflow and not a siphon, it makes sense. Only risk is a kink in the tube, or air gettin into the tube where it goes over the lip of the tank, or the airhole getting blocked?

 

[perle]

We discussed all of these issues above.

Tom, just to be clear, the system really is a siphon. However, it acts as if it is an overflow, because it does not have to be siphoning all the time. This is made possible by the special shape of the outtake tube. However your explanation is quite correct.

Jarred, I don't want to use an overflow. No modifications to the integrity of the tank! Plus I like the adjustable waterline.

And regarding the overflow issue, if the water pressure cuts out for long enough (at the same time I happen to be away for, what, 3 weeks? minimum?) to evaporate 4 inches of tank water, we have much bigger problems than water on the floor.

I live in an apartment. Sumps, gardens, overflow tanks, etc., are all very difficult to achieve.

Please read above. We discussed all of this in great detail.

Take care

~perle

 

[Jarred Darque]

I know you dont want an overflow, I wasnt saying that. I was just giving mroe insight into a truelly handsfree set up. You would need to have serious problems in order for your set up to mess things up, and if your gone for that long, I imagine you would have a friend feeding your fish who could take care of the siphon in the event that something happened

 

[perle]

No setup is every really hands-free.

~perle

 

[tbonem91]

Jarred - the RODI system, like I also missed, is powered purely by water pressure from the tap, not power. Even in a full blackout, this system runs fine. All systems have potential issues and it appears the only one here is the outlet getting blocked or kinked like Tom said.

When thinking about it, a minor issue in this system pales in comparison to all the water Ive dropped on my floors using buckets.... More times than I want to remember Ive forgotten that one of my buckets is filling in the bathroom and its overflowed all over the floor

 

[TomK2]

Tbone-

I did the same thing with my 30 gal holding tank. I just went upstairs for what seemed like a minute. Damage was limited by a slope in concrete floor and a drain in the floor about 10 feet away. What a mess.