Chlorine Drip System???

[big_g]

Ok, so I have this idea...that I'm sure someone else has probably asked about before. Probably a lot of someones...

But is there any reason I couldn't use a 5 gallon bucket, a small hose, a valve, and gravity to create a chlorine drip system that constantly dripped a very small amount of chlorine directly into my pool???

 

[JasonLion]

You could. I suspect that the drip tip would clog after a while, but it would probably be long enough between clogs that you could work out a schedule for cleaning it frequently enough to avoid problems.

 

[mas985]

I did this for acid but there are those who applied the same technique to chlorine:

homemade-acid-or-chlorine-injection-system-t4174.html

With a passive drip system, you would probably need to have the bucket and line near the pool. By using the pump to create suction, you can place this setup by the equipment.

 

[big_g]

Sweet. Thanks for the link mas985! Very helpful ideas in there.

I need to have the setup by my pool, since my equipment is in a separate yard that is in the sun 100% of the day. Not to mention my stupid dog that chews up everything.

My original idea was to either have the system drip 6% (or diluted to 3%) bleach into my skimmer basket, but could that hurt anything in there due to the high concentrations that would build up until my pump came on? (I run my pump from 5pm to midnight every day). Plus it would be kind of ugly...

Otherwise I have a return water line that runs when the pump is on (and I open the valve for it...). And it runs right in front of where I want to put my 5 gallon bucket. So I thought maybe I could rig something up where that return line flows through a separate small container of chlorine (on the end of my drip system) on its way to the pool?

Thoughts or suggestions? Thanks guys!

 

[mas985]

You could tap into that line but I suspect it is under pressure so here a few options you could explore.

1 - You could use a small aquarium check valve on 1/4" line so it shuts off the chlorine flow when the pump is on but gravity drains when the pump is off. As soon as the pump turns on it will push the chlorine which has accumulated in the pipe out the return. The downside of this it is more like pulse dosing rather than continuous. But a lot of BBBers do once a day dosing and it works for them. But keep in mind that gravity dosing is hard to control unless you have a drip IV setup of some sort.

2 - You could use a peristaltic pump if you have power nearby. This has very precise dosing control and can overcome the pressure in the return line. This might be your best option IF you have an outlet nearby.

3 - You could use a venturi injection system but that requires significant restriction in the return line to get it to work properly. I wouldn't suggest this route unless as a last resort.

 

[big_g]

I like #1. I was going to just try and control the drip rate with a valve. A perialistic pump looks great, but if I was going to start spending that kind of money I would just go to a SWCG (which I may still do next year).

My only thoughts are that the return line will stay full of water even when the pump is off (i.e. it does not gravity drain). So I don't know if the chlorine drip will enter the line in that case. So I think I might try and make a kind of reservoir above the level of the return pipe that the chlorine can drip into, which then empties when the pump comes on.

Like in the super-high-quality-architect-level drawing that I attached. :lol:

 

[mas985]

I don't think that will work because when the pump is on, the return pipe is under pressure so water will flow backwards into the reservoir and it will overflow. Also, the bucket with the chlorine/water will need to higher than the reservoir for it to drip into the reservoir so overall, I don't think that would be practical.

What I was suggesting for #1 was

Chlorine/Water Bucket -> valve -> 1/4" line -> check valve -> 1/4" line -> pipe injection

But again, this will have a variable flow rate as the bucket drains.

 

[big_g]

Well, the reservoir would be a sealed unit (I'd tap into it for the chlorine drip line), otherwise yeah it would overflow in a second. And the return line is at least 6 inches below where the chlorine bucket would sit, so gravity is in my favor there. The tricks would be the variable flow rate (good call, I didn't think of that one) and ensuring that the pressure in the reservoir when the pump is on does not pop off the drip line, either at the entrance to the reservoir or at the check valve.

I was thinking of just putting a tee into the return line and then using an appropriate-sized vertical piece of PVC (capped off at the top) as the reservoir. I can also control the pressure of the return line because it has its own main valve upline from where I would be teeing in.

So in the picture from my previous post... Picture the reservoir as a sealed unit (with the chlroine drip line tapped into the top) that is tee'd into the return line, which is pressure controlled. Since bleach is heavier than water, when the pump comes on the bleach will be sucked out of the reservoir into the return line (actually, the bleach may have already displaced the water that is sitting in the return line...). I think it will work...maybe... And if not I'm out a few bucks and a couple hours of (interesting) work.

See any more flaws? Again, nice catch on the variable drain rate! That would have thrown me off...

 

[JasonLion]

Bleach will not enter the reservoir when the pump is running. The pressure from the pump will probably be enough to send water backwards into the chlorine tank. Bleach will enter the reservoir when the pump is off, which will tend to drive the FC level in the reservoir very high, which will create a burst of high FC water when the pump turns on, which could damage something.

 

[mas985]

I had suggested a check valve in line to prevent back flow but that may not be enough to prevent the air evacuating in the vertical pipe since it is likely to move past the check valve before it seals. Once the air is gone, the system will at as a siphon instead of drip and then the vertical pipe adds no value so you might as well inject directly into the return pipe. In my mind, there is really no benefit to a drip system vs a siphon and control of the flow rate should be a little easier with a siphon because the pressure differential will be a little higher with the siphon.

 

[big_g]

Bleach will not enter the reservoir when the pump is running. The pressure from the pump will probably be enough to send water backwards into the chlorine tank. Bleach will enter the reservoir when the pump is off, which will tend to drive the FC level in the reservoir very high, which will create a burst of high FC water when the pump turns on, which could damage something.

Yeah, the pressure from the pump will keep the bleach from entering the reservoir, but that is actually almost desirable since that way I have a better idea of how much bleach will enter the pool (the size of the reservoir, approx). I am mostly worried about backflow pushing past the check valve into the bleach tank, but I think I can mitigate this by controlling the pressure of the return line with its valve, since I only need enough flow to push the bleach from the reservoir into the pool. The upside is that there is less resistence in the line to the pool than in the line to the bleach tank, so actually backflow to the bleach tank should not be an issue after all... Guess I'll find out pretty fast though, won't I.