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Thread: HOmemade acid/bleach feeder

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    HOmemade acid/bleach feeder

    I already tried this at home, now someone please tell me if it is too dangerous. I HATE pouring acid and liquid chlorine into the pool because of the heavy jugs, fumes, spills, splashes, etc. I have a liquidator, but still occasionally need to dump liquid shock or add acid.

    I disconnected my Liquidator and experimented with the intake fitting. I stuck the tubing into a jug
    of bleach and PRESTO, the jug emptied out at a controlled rate. I would like to I add another suction side fitting and valve just for this purpose and use this same method to introduce acid directly from the jug.

    I would be watching the whole time, I am not trying to automate the process, I am just trying to avoid the walk around the pool tricking dumping and choking.

    Concerns:
    Too dangerous because of the possibility of backsiphoning water into the jug? (in which case I would predilute in a bucket).

    Too much undiluted acid into the pump and filter? (use 1/4" tubing and lower flow rate...like 1 qt/5 min)

    Acid not distributed around pool?

    Will acid eat up valve, PVC, fittings?
    33' above ground pool, 52" deep, about 27500 g
    sand filter w/zeobrite

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    mas985's Avatar
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    Re: HOmemade acid/bleach feeder

    Here is what I did as well as some others that tried it. The important part with acid is the concentration. A slow low concentration constant feed is better than a fast short and much higher concentration.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: HOmemade acid/bleach feeder

    I read about your device with great interest. Sounds like a great solution for slow drip/maintenance dosing, but that isn't what I need. Routinely, my pool maintains ph pretty well, but when things get out of whack and I get a ph spike (high chlorine demand times, shocking, adding borates or other random events) I need something for when I need to get alot of acid into the pool in a short period of time to bring down elevated ph.

    How are your buttons and valves holding up to the acid? Do you have a problem with the acid/water solution degrading?
    33' above ground pool, 52" deep, about 27500 g
    sand filter w/zeobrite

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    JasonLion's Avatar
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    Re: HOmemade acid/bleach feeder

    You need to be very careful about feeding acid in before the pump at anything but very slow rates. Too much acid can damage the pump seals and the o-rings in the valves and filter.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    mas985's Avatar
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    Re: HOmemade acid/bleach feeder

    Ditto to what Jason said. This is the reason I went with this solution as it does not change the PH very much from input to output but enough to keep into a reasonable range.

    Quote Originally Posted by Miranda
    How are your buttons and valves holding up to the acid? Do you have a problem with the acid/water solution degrading?
    So far so good. I had a issue with the shut off valve and have since removed it as it wasn't really needed. If I need to shut off the acid flow, I just plug the hose.

    PH changes for a reason and it is usually gradual unless you are adding something to the pool which would change it in a short period of time. What do you think is causing the PH spikes?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: HOmemade acid/bleach feeder

    Exactly as you said, the pH spikes are usualy the result of adding larger amounts of Cl as needed occasionally. (startup, fighting mustard algae, liquidator flow "issues" etc.) I am replacing my liner so I will be adding borates to the new water and also going through acid/aeration protocol since my source water has an extremely high TA.

    I am disabled, so walking around the pool with a jug of bleach OR acid is precarious for me. I am looking for an alternative method for feeding larger quantities of bleach and acid on these occasions. I have looked into a venturi for the return side, but I got confused and gave up.
    33' above ground pool, 52" deep, about 27500 g
    sand filter w/zeobrite

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    Re: HOmemade acid/bleach feeder

    Jason, do you have any suggestions for a maximum flow rate into the suction side for acid? For example, if I set it up to suck in a quart undiluted over 10 minutes/30 minutes, would that be too much? I am trying to avoid the whole pouring/measuring/choking/spilling process, I want to be able to just stick a tube in the bottle and watch it, or set a timer and come back to it.
    33' above ground pool, 52" deep, about 27500 g
    sand filter w/zeobrite

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    JasonLion's Avatar
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    Re: HOmemade acid/bleach feeder

    I wouldn't feed more than 1 oz every ten minutes, and even that is without a safety margin. Everything is much simpler if you feed after the pump/filter/heater. Perhaps you could setup a Venturi injector after all the equipment, instead of using the pump suction.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: HOmemade acid/bleach feeder

    Here's just my opinion. Bleach addition is not usually a problem when adding at the pump suction but acid is a different situation. I suggest using a peristaltic pump in the return line after all the equipment. While a venturi works, it depends on the return flow staying the same to deliver a steady flow of solution into the stream. A pump system doesn't require a steady return flow.
    Dave J. TFP Moderator
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    Re: HOmemade acid/bleach feeder

    Thank you Bama for your help. I have looked for peristaltic pumps and haven't found a good deal. I think I prefer the venturi idea over the peristaltic pump, since consistency is not an issue for me (I want to get the CL or acid in there fairly quickly and I will be watching it the whole time...this is merely an alternative to dumping over the edge, NOT a maintenance dosing)

    Now which venturi parts should I use? This link shows PVC Venturi T's, I am assuming I could use the 3/4" T shown. I would use 1 2/2" >3/4" reducing T's to create a 3/4" parallel "circuit" with a balll valve in between the T's to choke divert flow to the venturi T. To the venturi T I would use a threaded bushing to insert a barb for a 1/4" acid line.... and add a 1/4" cutoff valve to prevent unwanted flow. When I need 16oz of acid, I will just turn on the vlave untiol UI draw 16 oz and then turn it offWill that do it, or is there a better suited product? Is there still a limit as to how fast I should add acid on the return side? Must I dilute it?

    http://www.lagunakoi.com/Venturi-Tees-P ... sc-159.htm
    33' above ground pool, 52" deep, about 27500 g
    sand filter w/zeobrite

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    Re: HOmemade acid/bleach feeder

    You description sounds about right. The finished setup should look something like this picture. These are fairly common on ozone systems, and the same setup will work for liquids.

    On the return side, as long as you are after everything (pump, filter, heater), you can feed quite quickly. All of the plumbing from there to the pool should be PVC, which can handle acid without problems, and once it hits the pool it will dilute extremely quickly. The only possible issue is acid left on the tube you dip into the acid storage bottle. So you will either want to leave it in the acid bottle, or have some way to rinse it off.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Mod Squad Bama Rambler's Avatar
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    Re: HOmemade acid/bleach feeder

    If I'm reading your proposal correctly, that sounds like it would work but I see they list a 1½" tee so why not just use it and reduce from 1½" to whatever size you need to adapt to the feed tube from the acid tank? If it's creating additional head in you main line I understand.
    Dave J. TFP Moderator
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    Re: HOmemade acid/bleach feeder

    Hanna Instruments makes a line of inexpensive diaphram pumps that will work to feed acid.
    7,500 gal, IG pool, L shape 22' x 15', 1.5 hp pump, cartridge filter, AquaPlus SWG/Controller, Pebble-Tec liner.

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    Re: HOmemade acid/bleach feeder

    Jason,
    Jason, I saw the Mazzei injectors which sell for about $50, as opposed to the linked venturi t's which are about $5. That was how I got confused. What is the big difference that makes the Mazzei parts special? I just noticed you are in Silver Spring. I was born on Dryden Street and raised in Olney. Got family all over Silver Spring. I flunked out of U of M Chemical Engineering School and remember just enough to be dangerous.

    Bama, as to the 1 1/2 T instead of the 3/4 T, if I understand the venturi concept correctly, the idea is to divert a portion of the flow to the parallel line including the venturi T. The T is narrower at one end, which sets up a pressure differential, which creates a vacuum at the reduction point. We need just enough vac to suck down a 1/4" line, so it seems to me that the 3/4" T should be more than adequate, and the 1 1/2" venturi T would be overkill. Does this make sense? Or is my reasoning way off?

    dschlic, I would like to see those pumps. Do you have a link? I couldn't find therm, i didn't know that diaphragm pumps could handle strong acids.
    33' above ground pool, 52" deep, about 27500 g
    sand filter w/zeobrite

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    Mod Squad Bama Rambler's Avatar
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    Re: HOmemade acid/bleach feeder

    You are right about it creating a flow restriction and in order to ameliorate that issue, a parallel branch circuit is the way to go.

    I typed up a big disscertation on why I don't like diaphragm pumps yesterday but thought better of it so I deleted it.
    Suffice it to say, if you can go with a perstaltic pump over a diaphagm pump you should.
    Dave J. TFP Moderator
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    Re: HOmemade acid/bleach feeder

    A Mazzei® injector has a small patented improvement over a venturi injector. They add twisting vanes that improve the efficiency. They are better, but aren't worth the extra money in this application.

    Here is some documentation on the Hanna pumps.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: HOmemade acid/bleach feeder

    The venturi idea hasn't worked out for me due to a piping configuration issue (no accessible return run long enough to connect to). I am working on TA reduction so I need to get alot of acid into the pool. I have been experimenting further with drawing into the suction side as follows: Fill 7 gallon jug with water, add 1 qt MA, stir. The 7 gallons of diluted acid is then drawn into skimmer line over the course of 1/2 hour. This translates to about 1 oz/minute acid (if it were undiluted) entering a 2" pipe carrying 40 gallons per minute. I collected and tested water from the return flow and found the pH only .1 lower than the rest of the pool.

    Jason, you suggested no more than 1 oz/10 minutes, so am I begging for equipment trouble with this setup? I must say, it works rather nicely as an alternative to dumping it over the side, which is just too dangerous for me with my disabilities. My next project is adding borax, so I need a safe method for adding alot of acid.

    I could dilute it further by slowing down the flow, using a larger container, or adding less acid to the jug at a time.
    33' above ground pool, 52" deep, about 27500 g
    sand filter w/zeobrite

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    Re: HOmemade acid/bleach feeder

    To have only a 0.1 change in PH and with a TA of 150, the acid ratio would need close to 320,000:1 but I think you have much more than that. I don't know much about your pump but if it is moving about 50 GPM, then the ratio of acid to water should be about 6400:1. So I would expect a much lower PH than what you are seeing.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: HOmemade acid/bleach feeder

    I tested my return water by testing water as it came out the fountain with a pH meter. I also tried the meter in the return stream underwater. My pool was ranged from about 7.5 to 8.0 and MOST the time I got a pH about .1 lower at the return. It did vary somewhat, but the biggest spread I got was .5 (7.5 when the pool was 8 and 7.0 when the pool was 7.5)

    6400:1 (by volume water to MA) sounds accurate, now how did you figure out what pH to expect for that concentration.? I was a chemistry major many moons ago but I forgot how to do those calculations.
    33' above ground pool, 52" deep, about 27500 g
    sand filter w/zeobrite

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