Building Chlorine Injector

Wolfmarsh

Well-known member
Jun 18, 2007
151
Charleston, SC
#1
Wasnt sure what section to post this in.

I am starting to think about designing a cheap way to constantly add bleach to my pool.

I have seen people using that liquidator, and also the pump systems.

All I am interested in really building is a system that will open a valve at certain intervals for a set amount of time, and I will adjust the timings if my chlorine trends upward or downware.

Knowing the flow rate of my system would also give me the ability to put a "+1 ppm" pushbutton on it that i press and it opens the valve for the right amount of time to let enough bleach to flow to raise my ppm up by 1, so if i test, or if i want to shock, I just go push the button the appropriate amount of times.

I have the solenoid valves, the tubing, and the electronics to throw this all together, what I am interested in is some suggestions for tank, or any features that might be nice for something small like this.


I was thinking of just getting a 5 gallon container (like one of those water cooler jugs), putting it in a wooden box near the pool (built up to look like a patio table or even a planter with a plant on top) and then running it that way.

I was also looking for suggestions on how you think I could run the line to the pool to get the bleach in it. I was thinking of maybe drilling a small hole in the return pipe and putting a fitting or something in there to attach the tube from the bleach dispensor.

Thanks for any thoughts/suggestions!
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#2
Without a peristaltic pump it is difficult to get consistent flow rates from the bleach reservoir into the pool. The pressure on both the suction side and pressure sides of the system will vary depending on the state of the filter so flow rates will tend to vary. There are a few companies that make special contant flow rate despite varrying pressure valves but they aren't common. A peristaltic pump with a suitable storage tank can be gotten for around $400-500, made by companies like Stenner. That isn't exactly the true DIY approach but they are very reliable and consistent.
 

JohnT

Admin
Mod Squad
TFP Expert
Apr 4, 2007
9,461
SW Indiana
#3
Injecting into the return line will require a pump. Otherwise you'd fill your chlorine container with pool water. The easiest way is to use the pressure difference across the filter like the Liquidator does to inject chlorine on the suction side. You'd also have to keep the tank cool some way to avoid large losses in strength. The Liquidator seems to have solved most of the issues.

You might be able to run a line into the skimmer and gravity feed into there.
 

Rangeball

Well-known member
May 25, 2007
785
#4
Why couldn't one use venturi suction with some sort of valving to control the outflow?

Similar to a pressure washer. Most have a plastic hose for injecting soap, etc into the spray.

Only for a pool you tap into a return pipe, run the hose from the line to a container and regulate the diameter of the hose via valving or similar to control bleach input?
 

Wolfmarsh

Well-known member
Jun 18, 2007
151
Charleston, SC
#5
Why couldn't one use venturi suction with some sort of valving to control the outflow?

Similar to a pressure washer. Most have a plastic hose for injecting soap, etc into the spray.

Only for a pool you tap into a return pipe, run the hose from the line to a container and regulate the diameter of the hose via valving or similar to control bleach input?
Thats exactly what I am going for. I would probably have to add a venturi injector in parallel with my return or something, but this is where I was headed. Either that or gravity fed. With gravity feed, the flow rate would depend on how full the container was, so thats something to take into account.

You'd also have to keep the tank cool some way to avoid large losses in strength.
I wouldnt think that having this stored in a box under the deck would be any hotter than my shed or my garage where I keep my bleach now.

This stuff has been worked on for years in the landscaping industry. The problem is always how to inject fertilizer or other chemicals into the irrigation system.

If I see the liquidator right, it is a modified pressurized mixing tank, with the lower port moved up to the top so it doesnt mix the tank like a fertilizer tank would be mixed up.

http://edis.ifas.ufl.edu/EDISImageP...dlNumber=WI004&tag=IMAGE WI:WI004F11&credits=
 

Steve #1

Active member
May 31, 2007
34
TEXAS
#7
I have all my stuff ready to go to install my chlorine injection system using a peristaltic pump.

You can read the details here .

I thought of other ways similar to what you are suggesting but I think what I am doing is easier, cheaper, and replaces the chlorine as it burns off so the level remains constant instead of having it bounce up and down by adding a dose after it has burned off.

In the post I linked to, I said I was ready to install it, but the install got delayed due to a death in the family and now I am swamped at work. I should have a chance to work on it again in a couple weeks.

I've got everything ready to go and have spent under $50. This includes the tap I had to buy and a role of Teflon tape.
 

Wolfmarsh

Well-known member
Jun 18, 2007
151
Charleston, SC
#8
Yeah, I also have decided to go the peristaltic pump route.

Gives me the ability to have the tank lower than the pool water line, under the deck where I can keep it cool and out of the sunshine.

Im just adding the circuitry for a small control panel, and a ppm per day display that will pump in the correct amount over the course of a day.
 

keithw

Well-known member
Mar 30, 2007
303
Virginia Beach
#9
I don't know why you wouldn't just buy a Liquidator, it has so many benefits IMO. I've had mine for about two months:

A. It's only $133.00.
B. A snap to change settings.
C. The cold pool water layer keeps the temps low so the bleach stays strong.
D. Adds a layer of water over the bleach to minimize fumes.
F. Takes no electricity.
G. Very easy to install and configure.
 

Wolfmarsh

Well-known member
Jun 18, 2007
151
Charleston, SC
#10
For some reason, I am still extremely skeptical of the liquidator. I cant really explain why.

Tell me more about it, and your experience with it.

Ive read the other threads, but still want more info. The info coming up in google is pretty lacking.

Do you have to add bleach outside of what the liquidator adds (other than shocking of course)?
How often are you finding you have to fill the liquidator up?
Do you find that it actually holds the chlorine level where you want it?
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#11
keithw said:
I don't know why you wouldn't just buy a Liquidator
F. Takes no electricity.
Actually, because it uses a pressure side to suction side bypass it reduces the efficiency of the pump ever so slightly, so it probably takes about as much electricity as a peristaltic pump would. In neither case is the electrical usage significant, so this isn't really a point in favor or against either approach.

It does look like a nice unit and the extensive discussion over on The Pool Forum is quite positive.
 

keithw

Well-known member
Mar 30, 2007
303
Virginia Beach
#12
To answer Wolfmarsh. Yes there is scant information on it. I was hesitant as well but decided it was worth the chance for $133.00. Since installing a little over a month ago, I have added no bleach outside of what I put into the Liquidator nor have I had to shock at all. I have been perfectly clear and have had a near perfect CL level continuously.

To Jasonlion: Yes I am sure that it probably does somewhat reduce the efficiency of the pump, but I would guess that is it very slight and for me was unnoticeable. My point with the peristaltic pump is that it is one more electrical device that can have a problem. Not to mention the fact that the decent ones are very pricey.
 

Titanium

LifeTime Supporter
Jun 26, 2007
441
SF Bay Area
#17
I do not have any experience with The Liquidator, and the information on their website is fairly scant.

However, The Liquidator is evidently manufactured by (or for?) HASA Inc. After a little research, HASA appears to be a fairly large supplier of pool and industrial chemicals. If anyone knows how to best apply sodiium hypochlorite to a pool, I would imagine it would be HASA.

Comments welcome....

Titanium
 

cruzmisl

Well-known member
May 26, 2007
185
#18
I've had my liquidator for about 10 weels or so and have been very happy with it. It is important however to watch the pH and alkalinity. If the pH gets too high you'll get deposits and it will gum up the unit. It's super easy to clean though.

My feeling on this whole thing is why reinvent the wheel? The Liquidator is not a perfect solution but one that is well executed and very simple in operation. By the time you factor in all the parts, time and effort involved you'll surely have more invested than $135. Having said that maybe you like to tinker and think of it as a challenge regardless of cost, in which case enjoy yourself :)
 

Steve #1

Active member
May 31, 2007
34
TEXAS
#20
cruzmisl said:
By the time you factor in all the parts, time and effort involved you'll surely have more invested than $135. Having said that maybe you like to tinker and think of it as a challenge regardless of cost, in which case enjoy yourself :)
Like I said, I've spent about $50 which includes buying a tool which I can use for other projects.

The Liquidator can't be controlled by a home automation system........ well, maybe it could. :)

Yes I like to tinker, but I don't think there is any more tinkering with a pump than the liquidator requires.

Why reinvent the wheel? I don't think using a mechanical pump is reinventing the wheel. It is the more common way of doing things such as this. I'll still throw out my usual response to "why reinvent the wheel" .... ask Robert Thomson.