Cloudy 18,000 Gallons With Good Test Scores

[Terri S]

I help maintain an 18,000 gallon semi-private pool. This is at a membership only campground.

In the last 2 days I have had a problem with the water clouding so badly that I cannot see the drain in the bottom of the pool. My boss and I are really baffled about this. We use Taylor's K-2006 test kit. This is what happened and what the test results were:

Sat 8/11 8am

Free Chlorine 5.0

Combined Chlorine .4

pH 7.0

Alk 100

Calcium Hardness 230

CYA 36

TDS 620

Temp 84.2f

I added 23 oz soda ash to raise pH level. The pool looked great.

4pm

Free Chlorine 2.2

Combined Chlorine .2

pH 7.3

I did not test the others. We usually don't in the afternoon. Just the Chlorine and pH.

I added 1.1 lb soda ash to the pool to raise the pH. This caused the pool to become so cloudy that I could not see the bottom step of the pool in the shallow end. I then cleaned the 2 next to the pool filters and socks, cleaned the in-line filter basket and back flushed (we have a sand filter). I also added 3 oz Super Clarifier.

By 7:30 am the next morning the pool was clear and beautiful.

8/12 7:30am

Free Chlorine 4.8

Combined Chlorine .4

pH 7.3

Alk 110

Calcium Hardness 240

TDS 632

Temp 83.9f

I added 23 oz soda ash to raise the pH (I have since found out that a pH of 7.3 is fine and I don't need to do that). The pool became cloudy again. There was no need to back-flush (the psi was 13).

Neither my boss or I know what is causing this. He thinks that it might be metals in the water, I'm wondering if the bottom drain might be clogged (the next-to-the-pool filter baskets are clean, as are the in-line basket filter and the sand filter, and the test results are within range).

Does anyone have any idea what is causing this, and/or how to prevent it?

Added: This also happened 3 weeks ago and we took the same steps that I took on 8/11. Also, my boss wants me to dump a gallon of muriatic acid into the pool tonight about 10pm.

Thank you.

Terri

Seaview, Washington

[Pathfinder]

Why does he want you do add the muratic acid??? There is no reason to do that considering your test of the water is fine the levels are ok.

Don not add that gallon Its only needed in extreme cases of high Alkalinity.

Tell your boss he's not a smart man and should take some courses.

Also shock your pool since your CC reading should be 0

[Terri S]

"Why does he want you do add the muratic acid??? There is no reason to do that considering your test of the water is fine the levels are ok.

Don not add that gallon Its only needed in extreme cases of high Alkalinity."

Thank you for this answer. I didn't understand why he was asking me to add it, your answer confirms that I am not going to do it.

I am going to try and get the manager of this campground to arrange education for us about pool maintenance. Neither one of us have done this before this campground. He's been doing this a couple of years, though, and mine is a matter of months. I'm reading everything that I can get my hands on, and asking questions.

"Also shock your pool since your CC reading should be 0"

I will do that. Thank you.

[OH Maven]

Hi Terri,

I am a Newbie, but you might have an Algae problem. I have a 30,000 gal pool and I add 9-10 oz of Algaecide a week to keep my pool clear. When you see Algae (in my case - Mustard Algae), then it is

out-of control. I think the water turns cloudy as the algae grows. I also put a clarifer in my pool (every 2 weeks) and that keeps it sparkling. You don't add it until you backflush first.

Jan

[chem geek]

Terri,

With the CYA at 36 ppm (are you estimating that from the K-2006 kit, reading between the lines, so to speak?) the minimum chlorine level would be 2.7 ppm with a decent target FC of 4.2 ppm so your chlorine level does seem fine at the start of the day unless you had mustard/yellow algae (which it doesn't sound like you have). However, it does sound like the FC level does drop below the minimum by the end of the day and that's not good (you reported 2.2 ppm FC at 4 PM).

Though it is true that dull water and then cloudiness can be from algae growth, the fact that you only see this cloudiness occur when you try and raise your pH by using pH Up tells me that this is just the normal situation of having a pool that is close to saturation in calcium carbonate (your pool's saturation index is around -0.2 when the pH is at 7.3 with the other numbers you reported). pH Up is identical to Arm & Hammer Super Washing Soda (careful: not the detergent) and is Sodium Carbonate. In the local area where it is added, it raises the pH quite a bit and also increases the Total Alkalinity (TA) by quite a lot (it adds a lot of carbonates). This makes the water cloudy. In fact, if you add it too quickly, you can even get solid pieces of calcium carbonate that fall to the bottom of the pool. Eventually, the cloudiness dissipates (usually over a day) and that seems to be what you are seeing and this is perfectly normal.

If you are using bleach or chlorinating liquid as your normal source of chlorine, then you do not need to have the TA be higher, so I'm guessing with the low pH that you had that you might be using Trichlor pucks/tabs, is that right? If so, then you need to not use them for too long as your CYA will climb (unless you do a LOT of backwashing regularly or have lots of splash-out). At any rate, most of the cloudiness you see appears normal. If you want to raise the pH without raising the TA as much nor have as much cloudiness, you can use 20 Mule Team Borax instead -- you use twice as much by weight to get the same effect as with pH Up. Or if you want to raise the pH with no change in TA at all, then just aerate the water and do not use an acidic source of chlorine (i.e. Trichlor).

If you want to know if you have algae, see if the Free Chlorine level drops overnight more than 0.5 ppm or 1.0 ppm. If it does, then you've got algae or some organics using up the chlorine and will need to shock the pool with higher chlorine levels -- 40% of the CYA level or about 15 ppm FC in your case -- using unscented bleach or chlorinating liquid. In any event, be sure to not let your chlorine drop below 7.5% of the CYA level ever. You might need a higher CYA level and correspondingly higher FC target to keep the chlorine from getting broken down as quickly by the sun, but before going that route make sure you aren't just using up the chlorine by a nascent algae bloom. You have reported some Combined Chlorine (CC), but not so much to be of concern (< 0.5 ppm is usually OK, though typically one measures only 0.2 ppm except after moderate to heavy bather load).

Richard