Homemade Acid OR Chlorine Injection System

JoeRJGR

Well-known member
Jun 19, 2013
138
Freehold NJ
Mark, sorry, I may have my terminology all screwed up....how can I tell the suction side from the pressure side, realizing I need to use the suction side? Also, I have been thinking about this, and is there any reason a brass needle valve would not work? I was also thinking of solving the temerature problem by using a large coleman cooler for my tank.....any issues with this thought process?

Thanks
 

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mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,733
Pleasanton, CA
Suction side is the pump basket and in the direction of the pump inlet (pipe entering pump basket) and towards the skimmers/main drain. The pressure side is from the pump outlet (top of pump) toward filter and everything beyond include the pool returns/eyeballs.

As for the valve, that might work ok for CL but not acid because of the PH.
 

JoeRJGR

Well-known member
Jun 19, 2013
138
Freehold NJ
Thanks so much!

I'm just going to set it up with a bucket or something and see if I can control the flow with just this $5.00 needle valve...right now I need about 1/2 gallon of bleach a day....if I can get it to do that,I'll try a 5 gallon buck, then a 10 gallon container....even if I need to end up going as high as 1 gallon per day in the middle of summer I'll be good for 10 days which is more then I need...

I'll report back...thanks again for your help
 

JoeRJGR

Well-known member
Jun 19, 2013
138
Freehold NJ
Got an accurate adjustment by using just this valve and some clear 1/4 " tubing. I have it taking 10 oz an hour or 80 oz a day. I may need to dial that back, but we'll see. I do seem to be having some draw after the pump is turned off...my pool water is probably at least a foot below my equipment. Would a check valve in the direction of the flow prevent this?

Thanks
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,733
Pleasanton, CA
No, a check valve is only useful if the tank is lower than the water level so it prevents flow into the tank. When the tank is above water level, you just need to account for the small amount of flow when the pump is off. Although some have dug a hole next to the equipment so the tank is below water level but in most cases, that should not be necessary.

Another option someone brought up was to use one of these very cheap peristaltic pumps. This will regulate that flow a bit more accurately but I think it would only work on the suction side of the pump.

New 12V Dosing Pump Peristaltic Dosing Head for Aquarium Lab Analytical Water | eBay
 

JoeRJGR

Well-known member
Jun 19, 2013
138
Freehold NJ
OK thanks...I'll measure it again tonight witha lid on it..just to exclude the fact that evaporation or my dog didnt drink the water..LOL...just not thrilled with bleach being sucked into the basket and sitting there till the next morning..

Thanks again mark
 

JoeRJGR

Well-known member
Jun 19, 2013
138
Freehold NJ
So the chlorine corrodes the brass to the point of stopping flow after 1 day...I wcan report that this valve does not work! May try the drippers...I know of at least one person who stopped using the drippers because they got glogged with a "white crud" similar to what I have heard about the Liquidator.....I wonder if you run clean water through it once a week if that would stop the problem? Anyone use the drippers for a long term solution?

Thanks
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,733
Pleasanton, CA
I do get some clogs in the buttons even with acid. Probably small dust/dirt. The buttons are reversible so I do that every fill or two and that seem to keep them clean. However, I reverse the entire chain because it is the first button that typically gets clogged and probably the same with CL.
 

JoeRJGR

Well-known member
Jun 19, 2013
138
Freehold NJ
Good tip...going to start that process today..couldnt find 1/2 gallon drios only gallon....I'll use way more bleach with a 38,000 gallon pool then most on here, so it should be OK.

Thanks again!
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
13,733
Pleasanton, CA
Initially, I used the water line compression fittings into the pump basket and they work well but they also degrade quickly with the acid solution.

Now I just directly inject into the suction line using aquarium fittings hot glued into the suction pipe. They seem to hold up pretty well. Also, if there is any draw during pump off time, it goes into the suction line instead of the pump basket.

5 PCS 2-Way Plastic Straight Connector for Aquarium Air Pump Line Tubing | eBay
 

Tul9033

Member
Mar 31, 2016
19
NE OK
Thanks guys, I ended up downloading the US plastics catalog and was able to find the fittings much easier. Unfortunately they only ship UPS so a ~$10 min shipping. I am getting several things so not too bad. I'm planning to get polypropylene fittings which should last longer than nylon.
Jaco Kynar®, Nylon & Polypropylene Tube Fitting Category | Jaco Tube Fittings, Kynar Tube Fittings and Nylon Tube Fittings. | U.S. Plastic Corp.


I'm testing the pump off draw right now. I do plan to dilute my MA 50/50.
 

know no

LifeTime Supporter
Jul 19, 2015
1
Houston, Texas
I am a complete newbie and have had a new pool for a year now. I am indebted to TFP for everything I now know. This is my first post, but I have been reading extensively here for the last year. I have never had the need to ask a question since I have invariably found the answer to every question I have had. I can't thank the members here enough for their questions and answers.

Since my wife doesn't like saltwater pools, I settled on bleach as my chlorine source. I obtained a Liquidator with which I suffered a very steep learning curve. I had all the problems described here with "white stuff" plugging hoses and valves, air leaks, etc. My chlorine delivery was so intermittent that I developed a black algae problem. Thanks to TFP, I have been able to get this all under control and become a confident and knowledgeable pool operator, today.

Every three days or so, I had to add about a gallon of acid to the pool. Of all my chores, handling hydrochloric acid is the most odious. It seems like I am always downwind of the stuff, trying to hold my breath, hacking and coughing. I wanted an acid feeder. I just couldn't understand why the equipment cost was so high. One of the available products required half-strength acid and I didn't like the idea of diluting the acid and having to replenish the supply twice as often. I decided to build my own acid feeder.

Dispensing a corrosive chemical like concentrated HCl against pressure requires a peristaltic pump, mainly to keep the acid away from the mechanical parts of the pump. Most of the pumps that I found after extensive Internet searching were not only quite expensive ($500+) but also unable to operate at the low flow-rate that I required. There is also the problem of finding a pump designed to use tubing that is chemically resistant in addition to displaying characteristics consistent with peristaltic operation (flexible but able to withstand suction pressure without collapsing).

I finally found a workable solution at a very good price point, SimplyPumps.com, Model PM216.
This pump uses 0.625"ID tubing with a flow rate of 35 ml/min minimum at 25 psi and suction lift of 20 feet. They can supply the pump with viton tubing which will work with the concentrated acid. The pump with the Viton tube set is $103. A 2-pack of replacement Viton tube sets is $22. Less expensive tubing can be used for supply and delivery. They also provide variable speed PWM power supplies for their pumps. The unit I bought for my pump sold for $24.

Rather than using the adjustable feature of the power supply, I chose to control the motor speed with the voltage control feature of the power supply. I found the control voltage that produced reliable pump operation and built a simple constant voltage supply for it. I control the amount of acid delivered with a solid state duty-cycle controller meant for heating and AC control.

The pump has been in use for about 2 months and holds the pH constant at 7.5 at 10% duty factor. I have not yet done any testing of the pH in the pool return during the on phase of the pump. The outflow of the pump is threaded into the 2" PVC return pipe with a 1/16"ID X 1/8"NPT adapter. I'm sure there will be a pH spike, but I expect that it will be acceptable, due to the high flow in the return pipe.

I adjust my Liquidator (10% bleach) with another duty-cycle controller connected to a 3/8" (1/4"ID) solenoid valve that keeps the pool chlorine at 6.0 with a setting of 4%. I have found that the larger ID is much less sensitive to debris than the standard flow meter.

After a year of effort, with the help of TFP, I can now leave town for a couple of weeks without having an expert watch my pool. It remains to be seen how all the parts hold up. I am checking Cl and pH daily. Necessary maintenance is an unknown at this point.

If anyone is interested, I would be glad to produce an article with details and photos about what has worked for me, if I can figure out how to do it on this system.
 
Last edited:

chesster51

Member
Apr 23, 2016
10
Middleburg, FL
I am a complete newbie and have had a new pool for a year now. I am indebted to TFP for everything I now know. This is my first post, but I have been reading extensively here for the last year. I have never had the need to ask a question since I have invariably found the answer to every question I have had. I can't thank the members here enough for their questions and answers.

Since my wife doesn't like saltwater pools, I settled on bleach as my chlorine source. I obtained a Liquidator with which I suffered a very steep learning curve. I had all the problems described here with "white stuff" plugging hoses and valves, air leaks, etc. My chlorine delivery was so intermittent that I developed a black algae problem. Thanks to TFP, I have been able to get this all under control and become a confident and knowledgeable pool operator, today.

Every three days or so, I had to add about a gallon of acid to the pool. Of all my chores, handling hydrochloric acid is the most odious. It seems like I am always downwind of the stuff, trying to hold my breath, hacking and coughing. I wanted an acid feeder. I just couldn't understand why the equipment cost was so high. One of the available products required half-strength acid and I didn't like the idea of diluting the acid and having to replenish the supply twice as often. I decided to build my own acid feeder.

Dispensing a corrosive chemical like concentrated HCl against pressure requires a peristaltic pump, mainly to keep the acid away from the mechanical parts of the pump. Most of the pumps that I found after extensive Internet searching were not only quite expensive ($500+) but also unable to operate at the low flow-rate that I required. There is also the problem of finding a pump designed to use tubing that is chemically resistant in addition to displaying characteristics consistent with peristaltic operation (flexible but able to withstand suction pressure without collapsing).

I finally found a workable solution at a very good price point, SimplyPumps.com, Model PM216.
This pump uses 0.625"ID tubing with a flow rate of 35 ml/min minimum at 25 psi and suction lift of 20 feet. They can supply the pump with viton tubing which will work with the concentrated acid. The pump with the Viton tube set is $103. A 2-pack of replacement Viton tube sets is $22. Less expensive tubing can be used for supply and delivery. They also provide variable speed PWM power supplies for their pumps. The unit I bought for my pump sold for $24.

Rather than using the adjustable feature of the power supply, I chose to control the motor speed with the voltage control feature of the power supply. I found the control voltage that produced reliable pump operation and built a simple constant voltage supply for it. I control the amount of acid delivered with a solid state duty-cycle controller meant for heating and AC control.

The pump has been in use for about 2 months and holds the pH constant at 7.5 at 10% duty factor. I have not yet done any testing of the pH in the pool return during the on phase of the pump. The outflow of the pump is threaded into the 2" PVC return pipe with a 1/16"ID X 1/8"NPT adapter. I'm sure there will be a pH spike, but I expect that it will be acceptable, due to the high flow in the return pipe.

I adjust my Liquidator (10% bleach) with another duty-cycle controller connected to a 3/8" (1/4"ID) solenoid valve that keeps the pool chlorine at 6.0 with a setting of 4%. I have found that the larger ID is much less sensitive to debris than the standard flow meter.

After a year of effort, with the help of TFP, I can now leave town for a couple of weeks without having an expert watch my pool. It remains to be seen how all the parts hold up. I am checking Cl and pH daily. Necessary maintenance is an unknown at this point.

If anyone is interested, I would be glad to produce an article with details and photos about what has worked for me, if I can figure out how to do it on this system.
Congrats on having the ingenuity to build that system, keep us posted on how it works long term. I too was having the white scale issue in my liquidator and added borate and it has been completely eliminated. I too had high acid demand but chose to go with the simpler liquidator style system, which is a 5 gal. jug mixed 4 gallons water to 1 gallon ma and injected just before the pump inlet and controlled with a Hayward needle valve. Both systems worked very well all summer long. During the summer the 5 gal solution lasted about 2 to 2.5 weeks keeping a constant 7.5 ph. Now that it's not as hot a full jug is lasting about 4 weeks.