Dirty pool water?

[trentdi]

Hi,

I have a 55k litre chlorinated pool with a sand filter. I try to keep the chemicals pretty balanced, testing every 7 to 14 days.

A couple of weeks ago my pool water turned from crystal clear to murky/dirty. The timing coincided with me doing some work digging up and resurfacing the lawn, work which blew a lot of dirt in the air, and resulting in exposing bare dirt (the dirt is still exposed as I wait for the new grass to set in). I initially thought that it was just the dirt blowing into the pool, and running the pump will clear things up. But after running the pump all day yesterday without any real improvement (and running the pump a bit longer every couple of days), I'm not so sure. Maybe there is dirt still blowing into the pool, maybe I just need to run the pump more, or maybe it's something else?

The chlorine levels have always been fine, and a test the other day showed chlorine still at 4ppm, which isn't all that high but should be sufficient. Because chlorine levels have always been good, I don't think a SLAM is needed or will do anything.

Is there any advice on what I should do, or should I just keep running the pump?

 

[PoolStored]

How are you testing your water?
What is your CYA level?

That looks like it needs to be SLAMed. If you doubt that and want to confirm, do an overnight chlorine loss test. Link-->Overnight Chlorine Loss Test

I'm surprised, even for late spring (for you), that you can go 7-14 days without adding chlorine.

If you pass OCLT, then you might consider adding POOL DE to your sand filter...may help with filtering.

Add DE to a Sand Filter

A clean pool filter will increase the efficiency of your pool! ... your filter are to backwash it, clean the manifolds and grids, and add new DE.

www.troublefreepool.com

 

[trentdi]

I've been using the test kit at Total Pool Water Testing Kit, Salt Water – Clear Choice Labs.

Just rechecked some of the chemicals:
CYA ~40
FC - 6
CC - 0.5
PH 7.6

Just added 7L of liquid chlorine and 1kg of trichlor. Also added 4L of liquid chlrone a couple of days ago. FC was 4 two days ago, and 4 on 14/11.

Given the CC (it was reading zero a couple of days ago) and the colour of the water, I agree that seems to need a SLAM. Just confused as to why given I've always kept FC above 4 (as measured by me). The soil I was working with was top soil so would be full of nitrogen - maybe that's what's caused it?

 

[PoolStored]

Just rechecked some of the chemicals:
CYA ~40

Great job on the test kit. Right on!

Maybe CYA is 40, maybe it was 50. The best on the CYA testing is to do the testing outdoors, sun at your back. Fill to each line, hold at your waist, then glance. When the dot is obscured at a particular line, take that number and add 10.

It is completely safe to run the pool at the top end of the "Target FC" WHEN YOU TEST. If you need to raise FC above the target, so that when you TEST, your FC is in the target range, do that. Min at 40/50 CYA is 3-4 FC. Better to run your pool at 7-8 FC with CYA of 40-50.

If my pool *sniffs* minimums it will cloud. Link-->FC/CYA Levels

FC was 4 two days ago, and 4 on 14/11

This implies that you tested on the 14th and the the 19th. Even though you are in early spring (down under), with lower FC demand, your testing of 5 days apart may be too infrequent, and likely too close to minimums. After the SLAM, keep your FC closer to 7-8 when you test (when your CYA is 40-50). Again, if you need to dose higher, so WHEN YOU TEST, you test 7/8 FC do that. With CYA of 40/50, FC up to 20 is safe for pool and swimmers. #TeamRunHot

 

[trentdi]

Thanks for the info and the hints on how to measure CYA with that test kit.

It sounds like I was too close to the min (but still not below), and I should keep things closer to FC 7-8.

But I'm not sure why you've emphasised 'when you test' (eg. at the top of the "Target FC" WHEN YOU TEST.... so WHEN YOU TEST, you test 7/8 FC). Are you saying that you can dose higher than the target range, with the expectation that that level will come back down into the target range when you test? FWIW I always tested the water before adding any chemicals, so the recorded levels were always the lowest of the cycle.

I was going to ask whether it makes sense that there's algae even with a CC of 0, but that has already been answered! No Combined Chlorine but water is a bit cloudy

Final question, you wrote: "your testing of 5 days apart may be too infrequent" - once the situation has stabilised, do you still need to test frequently? I thought I was getting a feeling for how much chlorine the pool needed weekly (which ended up being a bit wrong). I'd think that after a few tests that you'd know roughly how much to add each week... or is the rate at which chlorine is consumed just too variable?

 

[sande005]

PoolStored can answer the first questions.

As to testing frequency -
It depends....the big consumer of Cl is daylight (even on cloudy days), so as the days get longer, you need more Cl. As pool usage goes up, that too may need more Cl. Organics (dirt) can use it too, but usually far less that one would think. So a moving target, with more use during the height of summer and less in the early and late seasons. Highly dependent on the situation for your specific pool. They can go through 2-8 ppm of Cl per day, depending. So you need to get a feeling of what the pool needs daily.
Being new - I'd suggest testing at least 3-4 times per week, until you get a clear understanding. Then perhaps you can cut back to 2 times a week. Those that use liquid chlorine only tend to test daily, or at most every 2 days.
Note if you are using trichlor, that it adds CYA constantly, so that number will rise, requiring an ever higher target for optimal Cl. Eventually it will get so high that Cl adding is impractical, and you have to drain your pool to reduce the CYA level. Cal Hypo has no CYA, but the same issue in that it quickly builds up the calcium level, requiring a drain in the future. Liquid does neither - but requires consistent frequent testing and frequent additions. Hence why salt pools have become the gold standard....

 

[PoolStored]

Are you saying that you can dose higher than the target range, with the expectation that that level will come back down into the target range when you test?

EXACTLY!!!

Final question, you wrote: "your testing of 5 days apart may be too infrequent" - once the situation has stabilised, do you still need to test frequently?

Basic Pool Care Schedule

This basic pool care schedule can guide you in creating your own pool care routine. Regular pool maintenance will keep your water sparkling!

www.troublefreepool.com

 

[trentdi]

Awesome - thanks everyone for the input and advice!

 

[trentdi]

shocked the pool up to about 17fc. Fc dropped to 10 so brought it back up to 16. Kept the filter running all day and looking much better!