First tests with proper test kit; and is it time to replace some water?

[dailygenesis]

Just a follow up question but are there any effective filters you can attach to a garden hose to filter calcium out of water as you're adding it to the pool? I've seen a few things as I've searched around but just wondering if these are effective.

 

[Dirk]

Just a follow up question but are there any effective filters you can attach to a garden hose to filter calcium out of water as you're adding it to the pool? I've seen a few things as I've searched around but just wondering if these are effective.

I don’t think so, but let’s ask @JoyfulNoise.

Did you already mention: do you have a water softener?

 

[JoyfulNoise]

Short answer - no.

Few hose end filters do much more than remove a little chlorine and possibly iron. Most are so small that, even if they could remove minerals, you wouldn’t get more than 50 gallons out of it before it was exhausted.

The only effective way to remove calcium is a with a water softener. Either install a whole-house softener with an external line for the pool OR setup an RV water softener to use with your hose fill.

 

[dailygenesis]

Have you dabbled with CSI yet? That's the number you want to keep an eye on. You can get away with an elevated CH by reducing some other factor to keep your CSI in check. Typically that is pH. Do you have the Pool Math app? Have you played with the calculators? There is one for CSI. You can enter your levels to get your CSI number. Ideally it should be 0 for a non-SWG pool, but anywhere between -0.3 and +0.3 is fine. If you play with the calculator, you can see what lowering you pH does to your CSI with a CH of 575. Give it a go. You'll also see a big difference when you play with the temperature (which, of course, is not something you can manipulate, but you'll get an idea of what CSI will do in the summer vs winter).

I've been working on keeping the CSI in check and it's going well, but one complicating factor is the fact that we have the spa and we have been using it most nights lately as it's been cool but nice out. So my water temps are around 47-50 normally through the day but then I heat up the spa to 98. So, if my CSI is good for 48 degree water, it's usually a little out of balance for 98 degree water. Should I worry about this? I assume since only a small amount of water 98 degrees for an hour or two and the much larger body of water is 48 degrees all of the time, that I should balance for the 48 degree pool and just not worry so much about the spa. But just wondering if that's the correct approach. Am I leaving myself open to more scaling in the heater or something with the 98 degree water?

 

[Dirk]

Ah, you did all my typing for me. You have it right. An hour or two for a portion of the water at 98 doesn't count. Stay the course.

Keep in mind, the acceptable range for CSI is pretty broad. And to impact plaster you have to push CSI out of bounds pretty far, for months and months, before you'd see any real impact. Keep it between -0.3 and 0.3 and you'll be fine. If your main pool is in that range, I doubt even the spa itself at 90° is out of range.

 

[Dirk]

Yah, I did some quick Pool Math math. If your pool and spa were 48° with a CSI of 0, and then you heated your spa to 90°, your CSI in the SPA might jump to 0.39. All good. Depends on your actual numbers, or course, but like I said, you'd have to be way, way out of range for months straight before you'd consider this an issue. Besides, the actual safe range for CSI is -0.6 to 0.6. I use -0.3 to +0.3 because I like to be well within range. But technically, 3.9 would still be in the acceptable range.

 

[mgtfp]

Well, according to your PoolMath logs, CSI gets pretty high when pH hits the top, +0.52 even at 50°F. At 90°F that turns into nearly +0.9. That's very high, and once summer sets in, high CSI will become the norm. You should be thoughtful about your pH management, and maybe get TA a bit lower.

 

[Dirk]

+0.52 even at 50°F.

Yep, if your CSI is already close to either threshold, then you're not really keeping it in check. Shoot for 0.0 and then anything close is fine. That's why I use -0.3 to +0.3 as a target, so that any inadvertent events that throw it off won't push it outside the -0.6 to 0.6 range.

Actually, I use -0.3 to 0.0 in the summer, when my SWG is running, because an SWG pool likes a slightly negative CSI. But for your pool, with no SWG, then the -0.3 to +0.3 range is a good goal.

 

[dailygenesis]

Well, according to your PoolMath logs, CSI gets pretty high when pH hits the top, +0.52 even at 50°F. At 90°F that turns into nearly +0.9. That's very high, and once summer sets in, high CSI will become the norm. You should be thoughtful about your pH management, and maybe get TA a bit lower.

Yeah, I've been keeping the pH higher because with the colder water temps the CSI was out of whack at lower pH. My TA just went to 90 on the last test (was holding at 80 before) and that has made a bit of difference. I lowered pH a couple of days ago to 7.7 and CSI is right at zero when around 50 degrees which is where things stand right now, except in the spa when I heat it up.

Edited to say -- I did let it get up to 8.2 a week or so ago and that was too high so I see what you're saying. Generally I'm aiming to keep it 8.0 and lower.

 

[Dirk]

I think I mentioned previously: Pool Math has a CSI calculator, with which you can play with the various parameters that affect CSI. You can use this calculator to see the effects of raising and lowering pH and temperature and CH, etc, to see how they each affect your CSI. I use this calculator to strategize pH and CH levels throughout the year (throughout temperature changes), and when to exchange water.

 

[dailygenesis]

I think I mentioned previously: Pool Math has a CSI calculator, with which you can play with the various parameters that affect CSI. You can use this calculator to see the effects of raising and lowering pH and temperature and CH, etc, to see how they each affect your CSI. I use this calculator to strategize pH and CH levels throughout the year (throughout temperature changes), and when to exchange water.

Yes, I've been using this as well. I guess the gist of my question was just how to factor the temporarily elevated spa temperatures into my planning, which I think we've answered as -- the most important thing is the main pool in its normal state, but if it's possible to align it to keep the CSI at least in range when spa is elevated temporarily then might as well do that too.

Also, on a slightly unrelated note, I did all my tests again last night and my CH was down by about 50 PPM from a couple of weeks ago. That seems unusual, though I'd be relieved if it's really true. I guess I'll just test again soon to see if I can confirm it. Just seemed odd that it would go down so much without me doing anything. Haven't had much rain and haven't exchanged any water. Any thoughts?

 

[PoolStored]

I did all my tests again last night and my CH was down by about 50 PPM from a couple of weeks ago

Do you have a speed stir?

 

[dailygenesis]

Do you have a speed stir?

Yes

 

[PoolStored]

Yes

More likely than not, testing error. When you test make sure bottle is straight up and down. Sloooooooowly squeeze so drops fully form and drop on their own. Doing those two thing may make results more consistent.

 

[Dirk]

More likely than not, testing error. When you test make sure bottle is straight up and down. Sloooooooowly squeeze so drops fully form and drop on their own. Doing those two thing may make results more consistent.

That's likely. Other test procedure tips that can help accuracy and consistency:

- Sample pool water from a few feet down, mid-pool, away from skimmer and returns as much as possible.
- Once you establish the best place to sample water, always do so in the exact same spot.
- Before collecting a sample, rinse container with a sample taken from the same spot.
- Rinse all testing gear with the sample water before testing.
- Perform all tests in a consistent manner: once you establish your own "best practice" methods, use those exact same methods each time.
- Perform tests under the same exact lighting conditions each time (not outside).
- Rinse all gear with fresh water after completing testing.
- Store all testing gear and chemicals indoors in a dark, cool location (like in a cupboard).
- Never toss used test chemicals back into the pool.

While performing the CH test, as I approach the expected number of drops, I slow way down on the interval between drops to allow the color to fully form. It seems to me it doesn't do so as fast as some of the other tests do.

I made a simple "sample taker" out of a length of PVC and a couple of PVC caps with holes drilled in them. It allows me to grab my sample from well below the surface. It's also great in the winter when the water is cold. And it's much easier on my old bones than lying prone on the deck and sticking my arm down into the water.

I sample at least twice. The first time to rinse out both the sample container and my PVC pipe. The trick is to cover the hole in the end of the pipe before it is plunged into the water, then release the hole once fully lowered. The cap on top remains above the pool's water level. Then cover the hole again while removing from the pool. Release the hole again while holding the other end over the sample container. In this way, the sample is taken from depth, without any of the "higher water" getting into the pipe. I also use a Leslie's sample container. They get just the amount I need for testing, and the squeeze top makes metering out the correct test sample amount very easy and very accurate.

 

[Dirk]

PS. The Taylor CH test can be done using a 25ml sample, or a 10ml sample. The 10ml sample MO saves on reagent, but the 25ml sample MO is more accurate. I find the 10ml MO is fine for my needs, but you can use the 25ml MO (if you haven't been) to improve your results.

 

[PoolStored]

(not outside).

Except for CYA test which should be done outdoors.

 

[mgtfp]

While performing the CH test, as I approach the expected number of drops, I slow way down on the interval between drops to allow the color to fully form. It seems to me it doesn't do so as fast as some of the other tests do.

I noticed that, too. And I do exactly the same when approaching the expected drop count. It can easily take 1 or 2 seconds in the CH test for the colour to change after the last drop. Very easy to over-titrate.

 

[Dirk]

Except for CYA test which should be done outdoors.

This is part of the often-cited TFP instruction set for testing CYA. I just don't happen to agree with it. I only point that out to say that my statement was meant to include the CYA test, I didn't inadvertently include it.

I believe that testing consistency is at least as important as testing accuracy, because testing (especially CYA) is somewhat subjective and testing, for the most part, is about trends (is the test result number higher or lower than it's supposed to be). For example, once you establish that your CYA test result of "xx" works for your pool in maintaining and protecting FC, it doesn't really matter if the actual number is 30 or 50 or 70. What matters is that you maintain that number. And if subsequent testing shows a number higher or lower than your pool's target number, then you can address that number appropriately. That's why consistency is so important. If you do the test the same exact way each time, you can better rely on the result, and have confidence in that result when it reveals the number is trending up or down.

IMO, you cannot test CYA consistently by doing so outdoors, because both the ambient and direct light on the testing vial plays such a huge part in reading the result, Really, more so than any other Taylor test. When outdoors, there are different lighting conditions virtually every hour of every day, and some days those conditions vary wildly. And who can test at the same time every time? Frankly, I don't understand why TFP keeps pushing this MO.

I find it quite easy to test CYA indoors, and I do that under very repeatable lighting conditions, completely unaffected by time, day, cloud cover or season. I know that if testing in this way gets me a "70," then I'm good, my pool and its FC will be happy. It doesn't matter to me if CYA is actually 70 or not. If I get 60, then I use Pool Math to bring my pool back to 70. And I trust my testing not because I know 70 means 70, but rather because my testing MO is so consistent that 60 means I need to add CYA and 70 means I don't. Again, it doesn't matter if it's really 60 or not, it only matters that 60 means my CYA is low. Anywho, I know that's not the accepted way around here, I only know that works for me.

(If Mods would rather I not share my particular thoughts on this subject, you won't hurt my feelings by deleting this post. )

 

[PoolStored]

IMO, you cannot test CYA consistently by doing so outdoors, because both the ambient and direct light on the testing vial plays such a huge part in reading the result, Really, more so than any other Taylor test. When outdoors, there are different lighting conditions virtually every hour of every day, and some days those conditions vary wildly. And who can test at the same time every time? Frankly, I don't understand why TFP keeps pushing this MO.

Because this. Very roughly speaking, direct overhead sunlight is around 100,000 lux, strong indirect light (i.e. shaded from the sun) is around 10,000 lux, an overcast sky is around 1000-5000 lux but varies on how overcast (which is why a bright white cloud overcast is still OK), indoors is usually < 1000 even in a bright kitchen (more typically 500 lux). The CYA test, being a turbidity test is VERY dependent on lighting.

Lighting matters.

Here is where I think we can agree. If you get a standard solution (say 50ppm), and use it in whatever particular lighting that you can to get a standard visual. Then use that same lighting when you test and confirm a consistent visual to the standard, Good To Go.

If you can't get a baseline in whatever lighting, or can't get a standard, Taylor designed the test using outdoor lighting (confirmed by call to Taylor).

If you follow Taylor instructions, but do it indoors, you will get a much higher CYA value vs. actual. The lower lux does not illuminate the turbidity.