Chlorine Demand ? -- Switching To Bleach

[bob1966tb]

Hi All,

Ok -- after reading the recommendations from the knowledgeable people on this forum, I am giving up on TriChlor tablets and switching to simple bleach.

I will be purchasing a Hanna Blackstone dosing pump in an effort to automate the bleach delivery.

First -- here are my most recent pool chemistry readings:

CYA -- 160 [ Yup.... 3 years of TriChlor has raised the CYA levels !!!! ]

TA -- 151

Calcium Hardness -- 317

PH -- 7.4

I will be draining the pool [ 13,000 gallons ] to get the CYA and Calcium Hardness back to within acceptable limits.

NOW -- MY question:

I can purchase 4 different Hanna Blackstone dosing pumps. Anywhere from 1.5 liter per hour to 7.6 liter per hour.

1.5 LPH

2.9 LPH

5.0 LPH

7.6 LPH

I have no clue what size pump to purchase !!!

The Hanna pump will operate in tandem with my main pool pump -- which is probably 4-6 hours per day in the summer and 3-4 hours during the winter. Since I live in Arizona, the pool is NOT ever shut down.

Given that the Hanna pump delivers the above 4 different MAXIMUM dose rates and the fact that I can adjust the Hanna downward to only 10 % of the rated delivery -- which should I purchase ?

I plan on using 6 % household bleach as the sanitizing agent to be used with this pump.

I would appreciate knowledgeable suggestions on which pump I should purchase.

Many thanks in advance !

Best regards,

Bob in Arizona

[G-MAN]

I'm not sure which one to buy but your definitely going to have to play with this for a while to get it to work properly as far as run time and percentage of dilution. You may even need to put it on a separate timer. Bigger may be better as long as you can find a way to limit it's output if you have to. I'd be interested to hear how this works for you.

[biggz]

Hi All,

Ok -- after reading the recommendations from the knowledgeable people on this forum, I am giving up on TriChlor tablets and switching to simple bleach.

I will be purchasing a Hanna Blackstone dosing pump in an effort to automate the bleach delivery.

I plan on using 6 % household bleach as the sanitizing agent to be used with this pump.

I would appreciate knowledgeable suggestions on which pump I should purchase.

Many thanks in advance !

Best regards,

Bob in Arizona

'bob1966tb' Hi Bob, This system is interesting. I read that you can use common bleach, but I didn't know that a device was available to dispense it. I use a Hayward chlorinator on my pool with mineral additives to achieve a constant 0.5 PPM of FC. I usually increase this to 1.0 PPM because of the heat in Florida and the threat of amoebas. Are you also trying to achieve these low levels of free chlorine? You probably heard of Salt chlorinating systems, so I'm curious why you're not choosing that route instead.

[chem geek]

Bob,

Another alternative that is inexpensive ($133) and that people are happy with and does not require a separate dosing pump is The Liquidator from Hasa. It is talked about in this thread where you can find where to purchase it. You can use either bleach or chlorinating liquid with this unit and it uses the pump's regular flow for dosing (you adjust the rate of flow to the unit to adjust the dosage amount).

Richard

[bob1966tb]

Bob,

Another alternative that is inexpensive ($133) and that people are happy with and does not require a separate dosing pump is The Liquidator from Hasa. It is talked about in this thread where you can find where to purchase it. You can use either bleach or chlorinating liquid with this unit and it uses the pump's regular flow for dosing (you adjust the rate of flow to the unit to adjust the dosage amount).

Richard

[bob1966tb]

Bob,

Another alternative that is inexpensive ($133) and that people are happy with and does not require a separate dosing pump is The Liquidator from Hasa. It is talked about in this thread where you can find where to purchase it. You can use either bleach or chlorinating liquid with this unit and it uses the pump's regular flow for dosing (you adjust the rate of flow to the unit to adjust the dosage amount).

Richard

Good Feedback !

I have read about the "Liquidator" on the link that you provided. It seems as though the dosing adjustment is not very precise with this device. I also read that there is a fair amount of precipitates in the liquid tank that require frequent cleaning.

The Hanna pump is a positive displacement device that provides a well metered and easily adjusted output.

There is a reputable dealer on eBay that is selling this Hanna unit for $ 130.00. This price doesn't include the chemical tank nor the foot valve or injection valve. These items will add "about" $ 70.00 to the price -- so I am looking at approximately $ 200.00 TOTAL.

I prefer to go with a pure bleach dosing system -- to keep from having CYA increases that are a result of using TiChlor tabs. I just finished treating for a mustard algae problem that resulted from a HIGH CYA concentration without me properly raising the FC to compensate.

I guess what I really wanted to know is what ballpark amount [ in gallons or liters ] of 6 % chlorine [ bleach ] would be needed to add to a 13,000 gallon pool at say 85 F degree water -- per day. This information would help me to choose the correct pump.

I understand their are many variables, perhaps too many to make a suggestion.

I'll "probably" purchase the 1.5L/hour pump. This can be adjusted down to 0.15L/hour.

Given a 6 hour per day cycle time in the summer, I would be able to adjust the pump for as little as 0.9 Liter per day OR as high as 9 Liter per day of the 6 % bleach. If need be -- I could further reduce the 6 % solution by simply mixing with distilled water.

The pump dealer is taking orders for delivery in January -- so I won't have the system installed until then.

Thanks to ALL for the wonderful and informative feedback.

Best regards,

Bob

[chem geek]

The amount of chlorine loss does depend on many variables, but needing to add around 3 ppm FC per day would be a reasonable "high side" of loss at typical 30-50 ppm CYA levels. In a 13,000 gallon pool and with 6% bleach that's 81 fluid ounces or 2.4 liters per day. So the smallest pump at 1.5 liters per hour would certainly be more than enough. Ideally, you would run it a little bit each hour during the sunny part of the day so as to keep the FC level roughly constant. That not only minimizes the chlorine level you need, but minimizes loss to sunlight as well (since that's proportional to the FC level -- i.e. you lose X% of the FC level from the UV rays in sunlight).

Richard

[poolyeti]

I know I'm coming into the discussion pretty late and you have probably already bought your pump, but my reccommendation would be a Stenner peristaltic pump BDF series. It can be programmed to feed just the right amount of chlorine for your pool every day. They can be bought at a very good price from these guys .

[kcfanxiii]

a little late to be sure. i wanted to throw out the idea of an Autofeed A300 Automatic Chlorinator by Poolife. the tablets you use are cal-hy-po based, and contain no CYA. better alternative than bleach, which has problems keeping its strength if stored for an extended period of time. also i saw someone already posted about salt converters, but you might do some research into that alternative as well. try the pentair intelichlor.

[Chris W]

Normally, Cal-Hypo is not a good choice in AZ as the water is already very hard. The most common reason for draining and refilling a pool is probably excess CYA and corresponding algae difficulties, but the pool stores all blame it on excessive calcium buildup. 1000 ppm Calcium is not uncommon in AZ for water that's a few years old.