Another Water Balancing Nightmare

[shamus57]

Hello,

I have an in-ground pool/spa, southern California, quartz/plaster mix, jandy aquapure 1400 salt water generator, currenlty 3500ppm, running 80% of the time. The total linear feet is approximately 121. Average depth is about 5.5 feet. (deep end is about 7.5 feet and we have a baja reef at about 24"). I estimate the gallons at 22 thousand, but I could be off.

The pool is about a year old, and i've had trouble with the chemistry since filling it.

Recently, I started to have green algae.

My PH has always been super high, dark pink

About 7 days ago, I started adding PH down (again) by clearview (sodium bisulfate). I've been adding 10 cups per day in the morning to my spa, with the air-blower and pump going to circulate. The spa overflows into the pool. I've gone through the majority of my 50lb barrel of ph down.

5 days ago, I added 32 ounces of algecide (hoping the decrease in PH would help the algecide be more effective).

My test strips say the following:

Total Hardness, very high, 1000 ppm?

total chlorine, very low, 0 ppm

free chlorine, very low 0 ppm

ph, high to very high, 7.8-8.4

total alkalinity, high, 180 ppm

stabilizer, ok, 50ppm

I did a drop/chemical test (where you add drops of solutions to the pool water in the test tubes), and my chlorine is very light yellow, confirming the test strip.

Strangely enough, my swg has always performed well, and kept the chlorine high.

After adding 40lbs of PH down, shouldn't it be lower than 7.8 ish?

Does algecide affect chlorine?

Any assistance would be great.

Thanks,

-J

[quantumchromodynamics]

About 7 days ago, I started adding PH down (again) by clearview (sodium bicarbonate). I've been adding 10 cups per day in the morning to my spa, with the air-blower and pump going to circulate. The spa overflows into the pool. I've gone through the majority of my 50lb barrel of ph down.

Sodium Bicarbonate is not pH down. Sodium Bicarbonate is used to increase Alkalinity.

Sodium bisulfate (dry acid) is used to lower pH.

The blower is aerating the water causing the pH to go even higher.

[shamus57]

my mistake, sodium bisulfate.

[quantumchromodynamics]

First of all, stop using sodium bisulfate. Use muriatic acid. And, stop using the test strips. Get a good test kit such as the Taylor K-2006 as shown here http://www.taylortechnologies.com/products...&KitID=2230

The test kit comes with a very good book about water chemistry and a slide ruler to calculate your saturation index.

Add 2 quarts of muriatic acid to the pool and report back all of your chemical readings including:

Pool water test results needed:

Free chlorine

Combined chlorine

pH

Acid demand test result

Alkalinity

Calcium Hardness (Not Total Hardness)

Cyanuric acid.

Temperature

Accurate volume of pool (Not estimate)

Supply water readings needed:

pH

Acid demand test result

Alkalinity

Calcium Hardness (Not Total Hardness)

Dilute the 31.45% muriatic acid 10:1 in a clean plastic bucket before adding it to your pool. Always add the acid to the water and do not add water to the acid.

Do not run the blower.

_____________________________________________________

See this for a more accurate Saturation Index Calculation that accounts for salt level.

http://www.autopilot.com/images/pdfs/digital_manual.pdf

Use the chart below to determine your overall water balance. Test water for pH, water temperature, Calcium Hardness, Total Alkalinity, Salt Level, and use the equivalent Factors (TF, CF, AF, Constant) from the chart below to determine your Saturation Index. Adjust chemicals to maintain balanced water.

pH + TF + CF + AF - SC = SI

[chem geek]

The Pool Calculator has an accurate saturation index calculator that correctly accounts for salt level as well as TDS, temperature, etc. It closely matches the Taylor watergram, but works correctly for a range of TDS (salt) levels.

[shamus57]

will do.

I'll get some acid today and add it later tonight.

I'll buy the testing kit tomorrow morning (my dad has a wholesale account at a local supplier) and test the pool and report back.

thanks for the help.

[quantumchromodynamics]

You need to get your pH and your total alkalinity down, and your chlorine up.

Test your water for chlorine, pH and alkalinity twice a day and add either enough muriatic acid to lower the pH to 7.2 to 7.3, or add enough bleach to get your chlorine up to 5 to 7 ppm.

Use the acid demand test and the chart in the book that comes with the Taylor test kit or The Pool Calculator to determine how much acid to use.

Use regular Clorox bleach to increase your chlorine. Use The Pool Calculator to determine the amount of bleach to add.

Only add one chemical each time. If your pH is above 7.8, add the acid. If it is between 7.2 and 7.8, add the bleach, if needed. Wait at least 4 hours between additions of different chemicals.

Every time you add acid, the alkalinity will also come down. The pH will be reduced when you add the acid, but it will probably go right back up.

As the alkalinity comes down, the pH will begin to stabilize. Once your alkalinity gets down to about 110, the pH will not increase as much as before.

You can speed up the process by aerating the water with the blower. Aeration will cause the pH to increase with little effect on the alkalinity. If you use the aeration method, you can lower the pH to about 7.1 each time.

Determine the right target Alkalinity by using The Pool Calculator to determine your Saturation Index. Use a pH of 7.5 and the Calcium Hardness reading from your new kit. Use a target Saturation Index of 0.0.

You also need to check your salt cell for scaling and clean it as needed.

Please also include test results for Salt, Iron and Copper in one of your next posts.

Get a quart of Stain and Scale control and add it to your pool at a time when you don't have to add the acid or bleach.

Make sure that your pool stays clean, and run the pump and filter 24/7 until you get your chemicals balanced.

Dilute any chemical 10:1 in a clean plastic bucket before adding it to your pool. Always add the chemical to the water and do not add water to the chemical.

[PaulR]

Pool volume: With an average depth of 5.5' and an estimated 22K gallons, that works out to about 530 sq ft surface area for the water. Is that about what you have? Linear feet is not useful for calculating volume without also knowing the pool's shape.

pH: Your pH is stubbornly high because of the SWG (which tends to increase pH), the relatively new plaster (which tends to increase pH), the spa jets (which tend to increase pH while you run them), and the high TA (which will tend to increase pH).

The plaster now being about a year old, that effect should be tailing off, and the TA will drop over time as you keep adding acid. Muriatic will be better for this than dry acid, although handling the muriatic requires more caution. The effects from the SWG and jets will be with you always, so you will always need to keep an eye on the pH. But, it should improve over time as the TA drops.

The only caveat there is if you have a lot of evaporation (in SoCal I would expect that) and have to keep adding water, and that water has high TA, it will be a little harder to get the TA down.

Algae: The algae is because of the low chlorine levels. You need to supplement the SWG with bleach to kill off the algae. Don't bother with algaecides, chlorine is all you need.

--paulr

[PaulR]

Please also include test results for Salt, Iron and Copper in one of your next posts.

Get a quart of Stain and Scale control and add it to your pool at a time when you don't have to add the acid or bleach.

No, don't get the Stain and Scale Control unless you actually have metals in the water. Nothing in the posts so far suggests that this is a problem.

--paulr

[quantumchromodynamics]

A product like Jack's Magic the Purple Stuff contains HEDP (1-Hydroxyelthylidene-1, 1-diphosphonic Acid). This will help prevent calcium scaling.

Adding 20 to 40 ppm of borates (Sodium tetraborate pentahydrate) would also be helpful in controlling pH once the alkalinity is down.

[shamus57]

OK. I added 1/2 gallon of muratic acid at about 6 AM and left the pump running.

I purchased a Taylor Test Kit K2005 (they didn't have a K2006)

Pool water test results needed: I tested at approx 10 am

Free chlorine = 0 (totally clear result)

Combined chlorine = 1 or 1.5 (tough to tell, maybe I'm a bit color blind)

pH = 8.0

Acid demand test result = 3 drops to about 7.4 pH

Alkalinity = 13 drops or 130 ppm

Calcium Hardness (Not Total Hardness) = 55 drops/550 PPM ?? I did it twice. the first was about 52 drops or so. There were red "clumps" of stuff floating around before it turned a light blue/purpleish color, afterward there was still clumps of darker colored stuff floating around. very strange.

Cyanuric acid. 57 to 58 ppm

Temperature: 84 deg. Fahrenheit

Accurate volume of pool (Not estimate): still working on it.. 22,100 seems to be best guesstimate now.

Supply water readings needed: (not sure what you mean by this second set of measurements..)

pH: 8.0 ?

Acid demand test result: 3 drops / to 7.4 pH

Alkalinity: 13 drops / 130 ppm

Calcium Hardness (Not Total Hardness) / 55 drops / 550 ppm

Sat. Index: approx. 0.95

Thanks for all the help!

[quantumchromodynamics]

The reason for the purple endpoint for the calcium test is probably metal ion interference, most likely copper. Add 10 drops of reagent No. 12 and swirl to mix at the beginning of the test to minimize this problem. Be sure to include the 10 drops in the total count of reagent No.12 used, to get an accurate calcium reading.

The second set of readings that was requested was for your fill water. The water that you are using to add water to the pool.

Since your calcium is so high, I am assuming that your fill water also has high calcium. I recommend that you begin using softened water as fill from now on to start reducing your calcium to less than 300.

Right now, I would add two more quarts of 31.45% muriatic acid (verify percent). After 2 to 4 hours, add 7 quarts of 6.00% sodium hypochlorite (Regular, unscented, Clorox bleach).

Check your Chlorine, pH and Alkalinity every day. Keep your free chlorine at 4 to 5, combined chlorine at 0.0, pH at 7.4 until the Total Alkalinity gets to 100 and then keep it at 7.5. Use The Pool Calculator to determine your Saturation Index to determine the correct alkalinity based on your current calcium level.

Check the salt cell for scaling and clean as needed. Use the SWG for routine chlorination, and bleach for shocking or quick boosts as needed.

Dilute any chemical 10:1 in a clean plastic bucket before adding it to your pool. Always add the chemical to the water and do not add water to the chemical.

[quantumchromodynamics]

If you have a lot of calcium carbonate scale, some of the acid will be used up dissolving the scale until the scale diminishes. You have to be consistent with your daily testing and additions of acid until your Total Alkalinity and pH stay at the correct level.

[shamus57]

OK.

I pulled the swg. I notice it had a "no flow" error prior to removal. It had relativly minor scaling on the inside. I soaked it for 10 min in a muriatic acid/water solution, and now it looks great. I reinstalled and still got the "no flow" error. I cleaned the sensor with a mild solution of muratic /water and when I reinstalled, my salt reading went up to 4100ppm (from 3500ppm). I'm adding fresh water and draining old water as I type.

I also added 2 quarts acid (prior to finding out about the no flow problem), but I guess that will be diluted as I am adding new water.

After my ppm gets to 3500 or so, I'll retest and post the results.

[quantumchromodynamics]

I would not rely on the salt sensor. If your salt sensor uses conductivity, which depends on the level of Total Dissolved Solids (TDS), to measure salt, then your high total hardness will make the sensor read the salt level as higher than it really is.

You need to accurately measure the chloride ion concentration.

Get the Taylor test kit K-1766 as shown Here

Also, if you get a chance, could you test your supply water and post the readings for pH, Acid demand, Alkalinity and Calcium Hardness?

[quantumchromodynamics]

From the Jandy Manual:

6.5 Flow/Temp/Salinity Sensor Cleaning:

One time per year or as needed. It is rare but scale formations on the Flow/Temp/Salinity Sensor sometimes occur and will affect the accuracy of the salinity test.

1. Remove Flow/Temp/Salinity Sensor from the threaded PVC Tee or 3-Port Cell by turning counterclockwise or removing the union nut.

2. Brush with a mildly abrasive green fiber household cleaning pad. Contacts should be clean and bright.

3. Thoroughly rinse the Flow/Temp/Salinity Sensor with clean tap water. Replace and resume normal operation.

4. Turn power off and back on in order to recalibrate and reset Flow/Temp/Salinity Sensor. Reset anytime Flow/Temp/Salinity Sensor is unplugged.

Anytime the Flow/Temp/Salinity Sensor is connected or disconnected and reconnected, the AC power to the unit must be turned off and back on (Cycle Power). If power is not cycled, unreliable operation of the Flow/Temp/Salinity Sensor will result.

[shamus57]

WOW! it took awhile, but I removed enough pool water and added enough fresh water to get my ppm of salt back to 3500.

I added .5 gallons of muratic acid last night and 2 gallons of .6% no-scent chlorine this morning.

This evening's readings of the pool water are:

Free Chlorine=5 (the darkest reading)

Total Chlorine=5 (the darkest reading)

PH: 8.0

Acid Demand = 3 drops to 7.4

Alkalinity: 12 drops or 120ppm

Calcium hardness: 45 drops x 10 for 450

CYA: 58 ppm

Tap Water:

FC= .25 (really, really light shade of pink/red)

TC= 1.0 or 1.5 (tough to tell shade difference)

PH= 8.0

Acid Demand= 2 drops to 7.4

alkalinity: 12 drops or 120ppm

calcium hardness: 10 drops to blue x 25 = 250ppm (I used the 10ml sample this time)

[quantumchromodynamics]

Here is the test kit that I think you need to test your salt. I would not rely on the salinity tester in the unit until you verify it with the drop test kit. You can order the kit directly from Taylor.

I'm not sure why your pH is being so stubborn. Keep adding acid as needed to bring your pH down to 7.4 until your alkalinity is right, then maintain 7.5.

With your supply calcium at 250, I'm wondering how the calcium had gotten up to 550 previously.

How is your water looking now?

[quantumchromodynamics]

Also, double-check the percentage on the muriatic acid. It should be 31.45 %. Some acid is made at a lower percent. If it is a lower percentage, you will need to add more.

[shamus57]

I'll keep adding 1/2 gallon a day until it comes down.

What can I add to reduce my calcium level?

My water is looking better, still a algae bloom or two, but I keep sweeping.

I'll have to get the test kit for salt.

[quantumchromodynamics]

Here is a reference that says: "To lower calcium hardness, anhydrous trisodium phosphate may be used. One-pound trisodium phosphate per 10,000 gallons will lower calcium hardness 11 ppm."

I have never used TSP for lowering calcium. The phosphate combines with the calcium to form calcium phosphate, which is insoluble. It forms a precipitate and makes a mess. I probably wouldn't want to try it.

The best thing to do would probably be to use a water softener on your fill water. Over time, the level will decrease.

[quantumchromodynamics]

I recommend against using Trisodium Phosphate to lower calcium. There are just too many things that could go wrong and it would add a lot of phosphates into your water.

If you feel that the level needs to come down, you can drain some of your water and refill with softened water. Many water softener companies will rent water softeners for such purposes. Call and tell them what you are trying to do, and ask them if they could rent you enough tanks to do 10,000 gallons, or however much you think you need to do.

[quantumchromodynamics]

When I first saw your pool water calcium level of 550, I assumed that your tap water also had high calcium, probably above 350. If your supply water were above 350-ppm calcium, then a water softener would probably make sense.

However, with your fill water at 250-ppm calcium, I think that a softener is unnecessary. You can just dilute as needed. I would recommend that you avoid lowering your water level during the day as the heat and sun would put unnecessary stress on your tile and plaster.

If you do lower the water to dilute, it would be best to do it after the sun goes down.

Base your dilution aggressiveness on how much problem or risk you feel scale is creating.

Offset the high calcium with a lower Total Alkalinity and a pH of 7.5 to get as close to zero on the SI scale as you can. Use The Pool Calculator for the best results.

You might want to consider adding borates to your pool. A 30 to 50 ppm level will help stabilize your pH and will help prevent algae. You can get borate test strips Here

Here is a more accurate boron test from Taylor, but it should not be necessary. The strips will do just fine, and they are a lot cheaper, too.

For your pool, you would need about 50 lbs of boric acid as shown Here

The only caution I would have about the borates is, if you have a dog, or other pet, that drinks lots of pool water, then you might want to avoid the borates.

[quantumchromodynamics]

With the following:

pH = 7.5

TA = 100

CH = 450

CYA = 50

Salt = 3,000

Boron = 50

Temp. = 86 F

You should be pretty close to a near zero S.I. This should help minimize scaling and plaster dissolution.

[PaulR]

The Taylor K-2005 chlorine test is a DPD (red drop) test, not the FAS-DPD (powder and drops) test. The DPD comparator block tops out at 5. How confident are you that the FC is not significantly higher? The pH test will start reading artificially high if the FC starts going higher than about 10.

--paulr