Ornery cloudy water

[evalm2010]

Hi All, brand new here. I am someone who got a D in Chemistry in HS so please forgive me if I sound clueless. My husband and I recently moved into a house in Washington, DC with a pool with the following specs: 24K gal., white plaster, in ground/in door, sand filter, I have to get back to you on the size of pump and filter. Old house, old pool, original pump, filter, and heater. We’re talking circa ‘77.

We opened the pool with green algae and what not growing at the bottom. The local pool store told us to shock and chlorine the heck out of it. A couple of days later the water was blue and crystal clear with all the dead algae at the bottom. At the time, the pressure gauge indicates it's time to backwash and so before we even vacuumed the algae we began the process of backwashing. We followed the instructions to the tee but when we returned to filter mode, the jet stream started spewing cloudy murky water. The water is now blue and looks clean but very cloudy. We’ve been back and forth to the pool store and the water hasn't changed even after all the chemicals we've been advised to put in it.

Here's the most current reading taken 6/22/10 by the pool store:

pH - 8
TA - 110
FC - 5
TC - 5
CH - 460
CYA - 0 (we were told that since our pool is indoor the CYA doesn't matter, is this true?)

And here's the advice:

Add 3.5 pt muriatic acid, wait 15 minutes
then add 2.5 qt scale inhibitor

Thoughts??? BTW, thanks for this great website.

 

[loughps]

Welcome to TFP.

I don't know enough about indoor or plaster pools to give advice on the scale inhibitor, but I think the pH advice is good.

The biggest thing you can do to clear your water is to get a good test kit that can accurately measure your chlorine and other levels on your schedule. Additionally, pool store results can be inaccurate or inconsistent. I'd recommend picking up a Taylor K-2006 or TFTestKits.net TF-100, both are found online with the TF-100 being a better value for the volume of chemicals you get.

I'd suggest ordering your test kit and then posting a complete set of results. Since CYA helps stabilize chlorine against loss from sunlight, I think you probably aren't going to need that.

There are lots of experts on here who will soon be along to help with the specifics of your pool.

 

[zea3]

Are we talking indoor as in fully weatherproofed or indoor as in a glass or screened enclosure?

Likely what has happened was dirty water remained in the filter after back washing and was spewed through a return when the system was turned back on. When you have a really dirty pool sometimes back washing is not enough to clean the sand and you have to open up the filter and rinse the sand with a hose until the water is clear. If you raise the chlorine to shock level and run the filter 24/7 it should start to clear up again.

Also, was it a calcium hypochlorite based shock you used? Your calcium level is a little high.

 

[ssa]

Welcome to TFP.

Your PH & CH seems very high. It seems that your shock (as process) works.
It is the filter did not remove the dead algae from the pool. It does not sound
right that you got cloudy murky water on return.

Unfortunately I don't know much about sand filters. Some one else would be
able to help you on that.

 

[loughps]

Depending on how old the sand is in your filter, you may want to either clean it or replace the sand. You can also check for channeling as in this post. Additionally, if you multiport has a "rinse" setting, make sure you run it in rinse for a minute or two after backwashing.

 

[evalm2010]

Thank you all for your welcome and replies. @loughps we bought the Biogard Test Kit - 1200V this morning. We plan to use it after we added the chemicals tonight. Not sure if this is good enough or if we should get one of the recommended test kits from this site?
@zea3, yes it is totally indoor. It does get plenty of sunlight from the glass doors, windows and skylight though. I am beginning to think there is something wrong with the filter. It is very old and was the original filter installed when the pool was built in '78 or so. I don't know when the sand was last replaced or if it has ever been replaced . We're trying to get a recommendation on whether to replace it or not. I also don't know if the shock used was calcium hypochlorite based, all I know is that my husband last used around 8 bags of shock in granular form.
@ssa and loughps, the filter is so old it doesn't have a rinse cycle. It does sound like the sand is channeled. We've been running the filter 24/7. We'll be putting more chemicals tonight and see what happens tomorrow. It may be time to get a new filter.

 

[loughps]

Not sure about all the tests in your kit, but the most important one is the drop based FAS-DPD chlorine test. I don't think any of the BioGuard test kits have that. I'd recommend adding the drop based chlorine test and a CYA test if your kit doesn't have one. You can order those here. If you can return that test kit, I personally like the TF-100 test kit from TFTestKits.net.

 

[evalm2010]

Thank you loughps. Do I need the CYA test kit even if my pool is indoor? Sorry I'm new to this.

 

[svenpup]

Thank you loughps. Do I need the CYA test kit even if my pool is indoor? Sorry I'm new to this.

If your ever used (or plan to use) a source of chlorine that is stabilized (dichlor shock or trichlor pucks) you will want to measure your CYA to determine what your target maintenance and shock levels are.

 

[zea3]

Did the pool store test the CYA or did they assume there was none based on the fact that it is an indoor pool? If it is testing as zero and you don't plan to put any in then you don't need the separate test for it. If someone has put stabilized chlorine in the pool then you will need to test the CYA so you will know whether or not you need to drain water. Too much stabilized chlorine will raise the CYA too high and will require higher and higher chlorine levels to sanitize the water. The usual way to decrease excess CYA is to partially drain and refill with fresh water.

 

[loughps]

I agree with svenpup, if trichlor pucks have been used for chlorination or if you plan on using them or any stabilized chlorine, you should have that test. Otherwise, if you can have a test done to confirm that there is no CYA in there and you never add any, you should be fine without it. I'm just not sure I'd trust the pool store testing it.

Is the water a fresh fill? If not, do you know what's been used for chlorine in it?

 

[svenpup]

I have never had a pool store test my water, but based on the stories I hear on this site I imagine that their test kit (especially CYA) involves a chicken and a bunch of squares drawn on the floor with numbers written in them.

 

[evalm2010]

Wow, that's a good question. The test results always showed zero CYA but I never questioned if they actually tested it or not. The pool store is aware it is an indoor pool. The little test strips that we use always showed the CYA below 30-50 range. I know my husband uses the dichlor shock or trichlor pucks, I have to check which one. I suppose we should worry about the CYA levels then? I really should get a good test kit.

 

[loughps]

Doesn't matter which one he's using, you have CYA in your water and you need to test for it. Getting the right amount of chlorine in your pool is directly proportional to your CYA level. I'd bet the pool store didn't test for it; I'd bet it's higher than zero (at least the 30 - 50 your strip showed); and knowing how much there is will be important in getting your pool clear and keeping it that way.

I'd also suggest switching to liquid chlorine (bleach) for chlorination. This doesn't add any CYA to your water.

 

[Melt In The Sun]

Evalm2010, having a little bit of CYA (20-30 ppm) in an indoor pool is a good idea. You can get along fine without it as well. From another thread:

The Mermaid Queen has it right. The CYA/Chlorine relationship holds in any case. In an indoor pool we recommend CYA be between 20 and 30, and the more common practice is to have CYA at zero. When CYA is between 20 and 30, things behave much as you would expect given experience with an outdoor pool. But when CYA is at zero, things behave a little differently.

The main issue, is that when CYA is zero, a FC level of well below 0.5 is sufficient to kill algae, but gets used up way too quickly to maintain reliable sanitation. Therefore indoor pools, without any CYA, are actually routinely run above shock level, sometimes way above, so that the FC doesn't all get used up at the first sign of contamination. That leads to some additional complications, such as fading and wearing out bathing suits fairly quickly, that are never normally an issue in an outdoor pool.

You want a kit that can test for it.

 

[evalm2010]

Thank you all for the input. I think I'm slowly getting it. I'll be sure to get the right test kit. I'll look into what loughps recommended. In the meantime, we'll try to lower the pH and CH by adding the recommended muriatic acid and scale inhibitor. I can't wait to get this water balanced so we can switch to the BBB method. We've spent over $400 on chemicals already. Thanks again.

 

[frustratedpoolmom]

You want a min CYA level of 20, even for an indoor pool...and then maintain your FC accordingly. I do suggest you replace that kit with one of the recommended ones, and because your CH is so high, stick to liquid chlorine and avoid cal-hypo granular.

 

[evalm2010]

While I wait for the test kit to arrive, can I assume then that since my test strip shows my CYA below the 30-50 range (low) that it is around 20? And that since my FC at the last reading was 5, and according to the Chlorine/CYA chart my target FC with my CYA of 20 is 3, then I shouldn't put any more chlorine because it is on the high side? I removed the floating thingy with the tablet in it last night.

At what point do I start putting chlorine again? At .5? Also, when that time comes is it okay to switch to bleach then? Can I use the pool calculator to figure out how much bleach to put in there? We added the muriatic acid and scale inhibitor last night but didn't have a chance to test this morning (work always get in the way). But the water seems better. It is still very cloudy though and I can see the bottom in the shallow part. I can also tell I have to vacuum.

You all have no idea how much you're helping me. Thank you so much. Please tell me if there is something I am not understanding.

 

[evalm2010]

After adding the muriatic acid and scale inhibitor last night I tested the water today and here are the results:

PH = 7.4
FC = 5
TC = 5
CH = 250
TA = 120
CYA = <30

I ordered the TF 100 test kit today so hopefully I will have a more accurate results next time. But isn't this just about there? The water, however is still very cloudy. I am now convinced there is sand channeling. Can I ask a silly question? Is the water safe to swim in at this point? The kids are getting very antsy.

 

[loughps]

Until you get the TF-100, it's going to be hard to make sure you're properly shocking your pool. Keep hanging in there and once you get that and post results we can help get the cloudiness figured out.