Cloudy Pool with Low Alkalinity

[STXer]

Greetings from St. Croix,

I neglected my tile pool chemistry over the winter other than maintaining a good chlorine level and ended up with an extremely low PH and no alkalinity. My pool has been crystal free all winter but when I started adding sodium bicarbonate (in 2 or 3 pound daily increments) my pool clouded up the second day and still shows a low PH and no alkalinity two weeks later. I took a sample to a pool store this week and their computer test indicated every thing was normal other than the low PH and low alkalinity and the pool tech had no explanation for why the pool was cloudy a week after 2 daily additions of sodium bicarbonate. I have 2 fairly new cartridge filters in good shape that I alternate and the pool was crystal clear the day before I initially added sodium bicarbonate. Today, with still no alkalinity present and the water still somewhat cloudy, I added another 2 or 3 pounds of sodium bicarbonate (mixed with pool water in a 5 gallon bucket before adding to the pool) and within 5 minutes I could just barely see the bottom. The pool was drained and re-grouted 4 years ago and then refilled with distilled water. The pump has good circulation. I have been maintaining the pool myself for 12 years and have never had any issues other than occasional algae issues. The pool water temp is 82 F. The pool is lightly used and never has dogs in it. Any ideas?

 

[pinguy]

Hi! We need a reliable set of test results to be able to give you accurate advice. Pool store testing is notoriously inaccurate. Recommended kits are the TF100 (sold by this site), or the K2006 (amazon and some pool stores).

TF 100 Link

K2006 Amazon Link

In the meantime, I also suggest reading this article and coming back with any questions: Pool School - ABCs of Pool Water Chemistry

Once you get a test kit and the basics down, I promise pool maintenance is super easy! Welcome to the forum!

 

[Patrick_B]

Welcome STXer,

I have to say getting cloudy from BS is odd. So is filling with distilled, but it would explain your lack of TA. What do you refill with, and do you know what's in that water? Also, do you have a test kit, and what kind to get your own readings? Sorry I have more questions than answers to start, but we will figure it out. If you have a kit, all the numbers you can give us will help. Did you notice any clouding in the bucket when you dissolved the BS?

 

[jaduck]

Did you recently add Calcium, using Calcium Chloride or Cal Hypo?

 

[STXer]

Thanks for the interest!
1) From the photo of my pool you can see that it is so cloudy you can barely see the pool cleaner in 6 feet of water. For years it has been crystal clear, as it was the day I started adding the sodium bicarbonate.

2) I used 2 different kinds of test strips by different manufacturers and they were both pretty much the same results. The hardness and chlorine are the same. One strange result common to both is that the PH and Alkalinity tabs pre-test are shades of brown and post test turn bright yellow, which does not match the color of the lowest values provided on the bottle. Note that I inadvertently contaminated the smaller strip Stabilizer tab (bottom) when handling it well after the test but that it was bright yellow as well after the test.

3) The test results were from a reputable pool supply store here. When I took a sample 5 or 6 days earlier they told me the chlorine levels were too high and that was affecting the test results. I allowed the chlorine to decrease and took another sample with the same results as the previous week, so apparently the chlorine levels had no effect on the PH and Alkalinity sample results from their tests.

4) We depend on cisterns here for our water (except in the main towns) so when refilling a pool or when a house runs out of water we get a water truck delivery. The trucks get their water from the water and power company which used to be distilled (condensed water from the power generation steam turbines) but is now reverse osmosis water. I don't recall when they swapped from distilled. We can also get well water but the quality is very bad and not recommended for pools. I usually have to add 3 or 4 inches of water to my pool from my cistern at some point during the dry season and normally have to pump it down from rain water numerous times during the year. The pool deck is sloped so that any water on the pool deck does not run into the pool.

5) I have not added anything other than stabilized chlorine tabs to the pool in 5 or 6 months.

6) I typically clean my cartridge filter every 4 to 6 months based on the flow rate from my pool waterfalls. However, since I initially added the sodium bicarbonate I have had to clean the filters 3 times over the past couple of weeks.

7) I purchased a 50 pound bag of sodium bicarbonate from the pool supply store a month ago.

8) I suspect that some chemical reaction is preventing the sodium bicarbonate from dissolving and preventing the test strips from accurately reading, since my test just before taking the photos indicates no alkalinity and very low PH although I added 3 or 4 pounds this morning and the pool cloudiness worsened within minutes of the addition

 

[pinguy]

That's a beautiful pool deck.

The reason we recommend those specific test kits and not test strips/pool store tests, is that the methods we use to maintain and fix pools relies on accurate testing that you are able to do at home on the fly.

The solution to your cloudy pool is to do a SLAM, as described in the link below. However it's very very difficult to do this without one of the test kits I mentioned, test strips do not cut it in terms of accuracy or range. If you do a search for test strips on the forum, you will find several threads with smarter people than me explaining the issues with using them.

I realize $70 for a test kit seems high, but it will save you lots of money and frustration in the long run compared to relying on the pool store.

Pool School - SLAM - Shock Level And Maintain

 

[jaduck]

Can you get the Taylor test kit in St. Croix?

If we trust your pool store test, and for once I do, you have ZERO alkalinity, so any acid put in that pool will not buffer! I think your ph is really closer to 4 than 6. Color indicating pH methods only do a small range. You must use a different indicator for very acid or alkaline conditions.

 

[pinguy]

Can you get the Taylor test kit in St. Croix?

If we trust your pool store test, and for once I do, you have ZERO alkalinity, so any acid put in that pool will not buffer! I think your ph is really closer to 4 than 6. Color indicating pH methods only do a small range. You must use a different indicator for very acid or alkaline conditions.

On that note, I think it would be prudent to bring the PH/TA up with Borax or Soda Ash and Baking Soda while waiting on a test kit, since low pH can be harmful to pool equipment.

Reference this article for the chems to use:
Pool School - Recommended Pool Chemicals

Sodium Bicarbonate is the same as baking soda.

Use pool math to calculate the proper amounts when adding chemicals:
https://www.troublefreepool.com/calc.html

 

[Patrick_B]

If I understand you correctly, Im not yet convinced you need to SLAM the pool. Often, we see cloudy water as and indication of a coming Algae outbreak. This is always caused by a lack of Free Chlorine in your pool. You maintain the pool has been Crystal clear right up until the moment you added the BS right? It's odd for that to happen, but we don't know how pure it is, or what else is in the pool. I'm not sure how long the Chlorine has been lower, but again, I am not convinced you are getting Algae yet. The Chlorine doesn't change the hardness, or Alkalinity parts of the test, but high enough, it can interfere with pH. The addition of the BS is not preventing the strips reading accurately, they simply can't be trusted. Trust me, your pH is lower than 6.0 when they tested, as that is likely their low limit.

Given the water source, there shouldn't be much for reaction purposes to cause the clouding, but I suspect something in the pool, or the BS was there in sufficient quantity to do so. When you said distilled water, I wondered, but knew something had to be different given your location. Condensed Turbine steam would be precisely that, and it's pretty amazing to me this would be the water they sell. No matter, just a curious point. Depending on what RO water they are selling, it could be just as pure straight from the unit, but for our purposes it might as well be. These water sources have little to nothing in them we need for a plaster pool especially. This will make it very corrosive to plaster and unstable in any pool. When you add the effects of Chlorinating with pucks you wind up with very acidic water.

As mentioned, we need some results from a reliable test kit. I am not sure, but think...you may be able to order a kit from Stateside, but I will find out for you. I don't mean to sound overly dramatic, but you desperately need one to get this pool under control. Given your water source, and means of Chlorinating the finish will not last, and you'll have the major expense of a re plaster and more. The strips are just not trustworthy and the pool place is less concerned with the integrity of the pool than we are, or you wouldn't be in this situation. They may be oblivious to the facts as well unfortunately. I will get back to you on a kit the moment I find out, and if yes, you really need to order one right away. You don't want to keep guessing with strips and risk destroying the pool. The cloudiness may clear up on it's own, but right now it's honestly the least of your real concern. I'm also sending you a PM.

Adding this edit to ask, have you ever used any other chlorinating source besides the pucks, and what, if so? If their hardness test is accurate, and I am not sure it is, that number needs explaining. It certainly didn't come from steam turbine condensation, nor from an RO. Possibly some from the sistern water, but more information is needed.

 

[Patrick_B]

If you were a friend of mine in this situation, I would tell you to order the items below as fast as you possibly could. You can get them shipped, and they will get them to you pronto. The speed stir is a nice option I would tell you to splurge on, because it will help you tremendously. Get the XL option as well so you don't run low on these, or at the least, get more of the Free Chlorine test powder. Just suggesting that given your locale.


Test Kit, with options:
TFTestkits.net

Powder:
TFTestkits.net

 

[STXer]

Thanks for the interest! The water is my pool is about 4 years old, when I refilled the pool after it was regrouted. At that time I added the required chemicals to get everything in spec. My pool is leak free, and without any rain I might lose around a half inch of water per week to evaporation. But I doubt I have had to add water more than once or twice a year since then then. However, I do have to pump it down periodically after heavy rains to keep it from overflowing onto the pool deck and keeping the deck wet, so the chemicals do get diluted out from rainwater. Usually I do a fair job of maintaining the pool chemicals during the summer and fall when the water is warm enough for us to enjoy it and then pretty much ignore it during the winter and early spring (when the water temp drops down into the mid and upper 70s - I know I am a weenie), other than keeping it clean and adding chlorine tabs. I do allow the chlorine levels to drift up pretty high during the winter when nobody gets in the pool so I think that may be contributing to the issue with the PH this year. Every year I have to raise the alkalinity in the spring but this is the first time it has clouded up doing so, although a couple of years ago I did have an algae breakout will raising the alkalinity. I am beginning to think that the PH may be so low it is not allowing the sodium bicarbonate to fully dissolve so it is remaining suspended as very fine particulate and making the water cloudy. I have added probably 7 to 10 pounds over the past several weeks so there definitely has to be sodium bicarbonate in the pool. And I have checked that my test strips react to the sodium bicarbonate by mixing some in a bucket and checking it. I think I may ad some PH Up, or something similar, to see what effect that has on the PH. The pool surface is tile and the grout is mainly gone due primarily to my negligence but I plan to wait until next spring before regrouting.

 

[Patrick_B]

Yea, that would be expected running that kind of water, and if this were a plaster surface, it would have gone the same way of your grout.

Not sure the pH would keep the BS from dissolving and would expect the opposite. Without knowing more, I dont want to speculate on what is causing the cloudy water. Best of luck, and let us know what happens.

 

[STXer]

Update:

1) I purchased a container of PH UP and added about 12 ounces yesterday with no visible effect - pool is still super cloudy with no indicated alkalinity and no PH color indication.

2) I changed out the filter this morning with my spare clean filter and it plugged up in 6 hours as indicated by excellent water fall flow initially (all pump discharge is through the waterfalls) to a barely a trickle after 6 hours. No obvious debris on the filter pleats and they feel finger clean with no grit.

3) I filled a bucket halfway with cistern water a little while ago and checked it with a test strip: no chlorine, good hardness, PH 7.2, maybe a very slight hint of alkalinity. I started adding 12 ounces of pool water to the bucket and retesting. After each pool water addition to the bucket the PH went down with no indication of alkalinity. By the time the bucket was about half and half the PH was below the color change threshold (6ish I think), the chlorine was almost good, and no alkalinity was indicated.

To me, this proves that the pool PH is truly very low and the 10 or so pounds of sodium bicarbonate I have added over the past 2 weeks is not dissolving for some reason. When I add the sodium bicarbonate I always mix a small amount in a bucket with pool water to create a slurry and broadcast it around the round, adding maybe 3 or 4 pounds a day with the pump running.

I suspect that possibly the very low PH somehow changes the saturation point for the sodium bicarbonate which prevents it from dissolving, so it is remaining suspended in solution and plugging up the pool filter. Unless I get some other ideas I believe I will drain out half the water and refill with cistern water, which should raise the PH (since I know the cistern water PH is good) and maybe that will result in the sodium bicarbonate fully dissolving and the pool clearing. Any ideas or suggestions before I go this route?

 

[Patrick_B]

I've given you the best advice I can, and would tell any friend of mine to order a kit, and stop guessing at what might be going on in the pool or adding things and best guessing with strips. Please hear it in the kindest tone. This is my sincere and solemn advice to you. If you want to do it right this is the only way. The other kit we suggest is a Taylor K2006C and you can find it elsewhere if you want, but I nor nor anyone else on the forum want to guess at what you really need. The advice we give is based on solid test results and anything else is a stab in the dark.

 

[STXer]

Thanks Patrick for the response. I do understand your questioning the results of a test strip as there is no reasonable debate as to whether they are as nearly as accurate as a test kit. And I will probably order a test kit for future use. But in this particular situation where I am trying to resolve the cloudy pool issue before going off island for a few weeks and having a house sitter watch out dogs and pool, I think there are sufficient redundant indications of the pool chemical status to make a recommendation if there was one to be made. Multiple independent tests indicate that the chlorine level is acceptable, the calcium hardness is good, the PH is very low, and the alkalinity is very low. Combined with the fact that the pool was crystal clear until minutes after adding my second batch of sodium bicarbonate, and my bucket test results today that I believe verified the test strips were fairly accurate in indicating that the PH and alkalinity were very low, I don't see how a test kit that only tests for the same parameters would alter those conclusions. Obviously there have been other documented cases where adding sodium bicarbonate has resulted in a cloudy pool so perhaps my situation is the perfect storm of extremely low pH and no alkalinity. At any rate my situation is unquestionably the result of my failure to maintain proper chemical control of my pool. I just assumed that I am not the only person who has backed themselves into this situation and that perhaps there was an easy solution.

 

[Patrick_B]

Ok, fair enough. I understand where you are, but I must stress the strips really aren't near as accurate. At minimum, go back to that place or where ever, and get a simple OTO/phenol red pH kit so you can really be sure of the pH. You know what you've done in the past, and about where things land. I can't say for certain, and just didnt want to guess on the clouding culprit, but its got to be a reaction from adding the BS whatever the precise cause. Never was worried about Algae based on all we knew, and Ive just been worried about the pool with no buffering capacity, and such low pH. Go with your plan to raise it, and do at least get the little pH tester so you can be confident in leaving with a decent pH in the pool.

 

[Jeremyhawkins]

Did anyone figure this out? My water has been perfect for a month and my TA was low so according to calculations I was supposed to add 5lbs a day for 2 days of sodium bicarbonate and as soon as I added 5lbs my water clouded up. My cya is 60 my TA is 74 my total chlorine is 5 and my fc is 5 hardness is 122 and my ph is 8.0

 

[Patrick_B]

No Jeremy, we didn't.

Please start a new thread, post all those numbers up, and Calcium if you have it, and we will try to get you an answer there. This was an unusual situation, and we just don't know.