Why is my pool so dirty!!!

[Charrua2]

[EDIT] I sent a detailed E-mail with many links to Goldline Controls suggesting, among other things, that they recommend a minimum FC level of 3 ppm (or even higher) with their 70-80 (where they say 80 is recommended) ppm CYA. I have also brought up other issues such as lower TA levels to reduce the rise in pH (they recommend 80-120 which is too broad a range -- should be 80-90). I also mentioned different salt cell designs with more plate area that could operate at lower CYA efficiently and referred to incidents of higher corrosion of coping/hardscape and metal (stainless steel poles in the pool and copper in heat exchangers) and possible ways of mitigating that problem or at least mentioning its possibility. These are all issues we have discussed at length in this forum (mostly in The China Shop). We'll see what they have to say. [END-EDIT]

Richard

Richard,

A quick question since I struggled this year with PH continuously sliding up after having incorrectly assumed that I could avoid this by raising the TA to 120 (prior to reading your comments that lower TA could reduce this upward movement in PH). I can only find where you clearly state that it is not a problem to lower your TA to even 50-60 for a liner pool. I have a gunite/plaster pool and was wondering whether it is also safe to have TA at those low levels. Thanks.

Alex

[bizbad]

Just wanted to report in. I chose to raise the clorine level to 35 ppm for 60 hours with pump running. I brushed each day. It has been two days since I stopped brushing and it still looks good. If I dont need to brush tomorrow I will know that I have won the battle. I am going to add Borax to the pool next week to see if I can level off the acid usage and provide some algecide benefits as well. I hope it works! Thanks for help.

[chem geek]

Just wanted to report in. I chose to raise the clorine level to 35 ppm for 60 hours with pump running. I brushed each day. It has been two days since I stopped brushing and it still looks good. If I dont need to brush tomorrow I will know that I have won the battle. I am going to add Borax to the pool next week to see if I can level off the acid usage and provide some algecide benefits as well. I hope it works! Thanks for help.

Great news about your pool getting cleared! You'll know that you've gotten all the algae if your FC level holds up overnight (or not in sunlight) and you have no (or < 0.5 ppm) CC. The 35 ppm probably worked because you started out at a little lower pH and, most importantly, the temperatures are cooler now so the algae isn't growing as fast. At any rate, it's good to know.

Don't forget to lower your TA to 90 or even 80 as that will also help. Follow the procedure at this post to lower your TA.

Your biggest problem now will be how to get your FC level back down if there isn't any sun to break it down, but technically with a CYA of 70 ppm and an FC of 35 ppm, the disinfecting (and oxidizing) chlorine level is at the same level as it would be if you had 1.0 ppm FC with no CYA. Though I would be confident enough to actually swim in such water, I'm a nutty chem geek. There's always the possibility that the chlorine bound to CYA does something nasty we don't know about (though it doesn't show up in ORP sensors, doesn't seem to kill any bugs, doesn't seem to oxidize anything, or do anything else that is detectable...). I did find that one can use hydrogen peroxide to lower chlorine levels rather than using sodium thiosulfate, so that was good news.

Richard

[chem geek]

Richard,

A quick question since I struggled this year with PH continuously sliding up after having incorrectly assumed that I could avoid this by raising the TA to 120 (prior to reading your comments that lower TA could reduce this upward movement in PH). I can only find where you clearly state that it is not a problem to lower your TA to even 50-60 for a liner pool. I have a gunite/plaster pool and was wondering whether it is also safe to have TA at those low levels. Thanks.

Alex

Alex,

If you lower your TA, then you make the water more corrosive in terms of gunite/plaster/grout so you would need to compensate by increasing Calcium Hardness (CH) or keeping the pH higher or both. However, you generally don't run into problems with corrosion (or scaling, in the other direction) until the saturation index is quite a bit out of whack. Nevertheless, if you post a full set of numbers, especially for your pH, CH, CYA, salt level or TDS, current TA, and temperature, then I can give you an idea of where you are currently at and what you can do after lowering the TA.

Richard

[Charrua2]

Alex,

If you lower your TA, then you make the water more corrosive in terms of gunite/plaster/grout so you would need to compensate by increasing Calcium Hardness (CH) or keeping the pH higher or both. However, you generally don't run into problems with corrosion (or scaling, in the other direction) until the saturation index is quite a bit out of whack. Nevertheless, if you post a full set of numbers, especially for your pH, CH, CYA, salt level or TDS, current TA, and temperature, then I can give you an idea of where you are currently at and what you can do after lowering the TA.

Richard

Thanks Richard,

Haven't tested the water since I closed it but I can tell you that the numbers usually were as follows:

FC = 2-5 (I rarely shock)
CC = 0
CYA = 40
Salt level or TDS = ? (never tested for this)
TA = 100 - 120 (used to be 90 and I raised it to 120...After that it lowers when I add the acid but then creeps up)
PH = 7.6 - 8.0 (added acid once a week...PH always creeped up but the upswing was quicker after I increased the TA)
CH = 350
Water temp = 75-90 degrees depending on month

Other info that might be of use: I only use bleach and I don't have a heater.

Thanks again

[chem geek]

Charrura2,

In your situation, you can lower your TA to 80 or even 70 with absolutely no problems (even if you did have a heater, which you don't). You can do that (following the procedure at this post) when the temps come back up since trying to lower your TA when temps are low can be more difficult. The lower TA will definitely help your battle of rising pH and you should be able to keep your pH around 7.5 without too much difficulty. Your CH is already elevated at 350 and helps compensate for the lower TA that I am proposing so your water will be in near perfect balance at the lower TA levels (currently, your water is over-saturated with calcium carbonate, but not so much as to cause cloudiness or scaling).

Richard

[Charrua2]

Charrura2,

In your situation, you can lower your TA to 80 or even 70 with absolutely no problems (even if you did have a heater, which you don't). You can do that (following the procedure at this post) when the temps come back up since trying to lower your TA when temps are low can be more difficult. The lower TA will definitely help your battle of rising pH and you should be able to keep your pH around 7.5 without too much difficulty. Your CH is already elevated at 350 and helps compensate for the lower TA that I am proposing so your water will be in near perfect balance at the lower TA levels (currently, your water is over-saturated with calcium carbonate, but not so much as to cause cloudiness or scaling).

Richard

Thanks Richard,

I had read in another post where someone even lowered there TA to 50 to really fight the rising PH. Next summer, if I see that TA of 70 still doesn't do the trick, can I try lower or should I avoid the risk?

Promise this is the last question.

Thanks again

Alex

[chem geek]

Remember that TA is composed of all alkalinity, both carbonate alkalinity and the alkalinity from CYA (and other lesser components) so even 70 ppm TA is risky if the CYA is high (i.e. 70-80) while at a lower CYA of 30 ppm then 70 ppm is OK. A 50 ppm TA even with a low CYA of 30 ppm, is on the corrosive side (not terribly -- just my being picky), and though this can be mitigated by running a higher CH and a higher pH, I would only do that if the rising pH was a really bad problem. At 50 ppm TA, a CH of 400 and a pH of 7.6 (instead of 7.5) would be better.

Richard

[Charrua2]

Remember that TA is composed of all alkalinity, both carbonate alkalinity and the alkalinity from CYA (and other lesser components) so even 70 ppm TA is risky if the CYA is high (i.e. 70-80) while at a lower CYA of 30 ppm then 70 ppm is OK. A 50 ppm TA even with a low CYA of 30 ppm, is on the corrosive side (not terribly -- just my being picky), and though this can be mitigated by running a higher CH and a higher pH, I would only do that if the rising pH was a really bad problem. At 50 ppm TA, a CH of 400 and a pH of 7.6 (instead of 7.5) would be better.

Richard

Ok, so it looks like if I go the route of lowering the TA to 70, I will have to keep on top of the CH a bit more than in the past. It's something I used to test once a month since it never really seemed to move way out of wack (ie, always between 300-400).

We'll see how it goes next year. Thanks once again.

[Charrua2]

Remember that TA is composed of all alkalinity, both carbonate alkalinity and the alkalinity from CYA (and other lesser components) so even 70 ppm TA is risky if the CYA is high (i.e. 70-80) while at a lower CYA of 30 ppm then 70 ppm is OK. A 50 ppm TA even with a low CYA of 30 ppm, is on the corrosive side (not terribly -- just my being picky), and though this can be mitigated by running a higher CH and a higher pH, I would only do that if the rising pH was a really bad problem. At 50 ppm TA, a CH of 400 and a pH of 7.6 (instead of 7.5) would be better.

Richard

Richard,

I opened my pool this season and am in the process of lowering the TA to 70 (as mentioned above). One number that changed over the winter season is the CH which is now at 175. I have purchased 8 llbs of Calcium Increaser from Walmart which should raise the CH to approx. 200. Should I raise it more or keep it there. My guess is that CYA is at appox 20 (dot never disappears completely but FC has not diminished too quickly). What do you think? As always, thank you.

Alex