Not able to sustain FC levels - Help!

[blueskyup]

Hello,

I have been having issues the last 1-2 seasons in maintaining my FC levels. It seems no matter what I do i'm not able to keep my chlorine at the required levels. This is the first season that I have been majorly involved (Buying chemicals, taking in water samples, etc) with the pool. I have started to get fed up with continuously dumping in chemicals and not getting any result which is why i'm posting on here. As an overview my pool is about 110,000 Liters. I have a variable pump with standard filter, vinyl liner. The pool is located in central Canada - The pool is open from May - September and closed for the rest of the year.

For pool maintenance I have been using Bioguard chemicals. Specifically 6 tablets/week in skimmer, 6 bags of smart shock (Oxidizer)/week and 220ml of banish/week (Algae treatment). In addition i take pool samples in monthly and use other chemicals as required to adjust PH, Total Alk, etc.

This season I noticed the problem after doing shock with power chlor (Trichlor) product as recommended from the pool store. After these shocks I would get my FC to go up but it would not maintain itself for man than 2 days. As a note my CYA level was about 50ppm when I opened the pool up this season and started with the shocks. After a few more attempts the pool store performed a chlorine demand test and determined my pool was in Demand. I followed the instruction from the pool store and purchased 15kg of powerchlor (65% Available Chlorine) and added about 1.5kg in the morning, afternoon and night for 3 days. I took pool samples in every day to check the FC and TC levels. On day 3 I had a FC of 4, TC of 4 - I thought and the pool rep thought the problem was fixed. 4 days went by and my FC went down to .3 and TC was 1. At this point I was ready to throw in the towel. One item to note is that during this entire time we had 0 bathing load. Also, i didn't know this at the time, but because we were using power chlor (A trichlor type of chlorine) I was steadily adding CYA into my pool. By the time I had done all the shocking my CYA was at 150!!! During the entire pool year I only had cloudy water once. The time I did have cloudy water was because of chlorine demand - based on what the pool people said.

At this time it was already the beginning of August. Our next solution was to either do another BIGGER shock or empty the water. I figured that since the season was pretty much over I would empty the pool 70% (water is cheap), shock it, fill it up to winter level. In hindsight I made a mistake of shocking it after I emptied it..I should have waited until it was full so the water would be more diluted and I would have a lower CYA. Anyways, I shocked it with 4 kg of breakpoint 35 (Lithium Chlorlite), which i found it much better to use because it does not affect your CYA. After the application my FC shot up to 8ppm and then in 2 days I was back at 1 FC and 3 TC. At this point I started looking at the forums on this site.

Based on the info above and what I have read on this site I think I have an algae problem that hasn't been fully dealt with. To make the issue worse I don't think the CYA has helped. The article I found on this website to most identify my issue is a respnse from JasonLion (Effects of high CYA on chlorine demand). I have already had arguments with with my pool store regarding CYA.. They seem to think an acceptable level is between 30-ppm and 200-ppm. I have further tried explain that chlorine effectiveness decreases as CYA increased (based on the CYA / Chlorine Chart). They don't even respond. I can't believe they kept pushing me to a Trichlor shock in lieu of a lithium chlorlite. To me this would explain why i'm not able to maintain my FC level. I do question however that at the start of the season I had decent level CYA (50ppm) but still had issues with my FC.

As of today I refilled the pool back up to winter level. The results for the last few days are below. One thing that doesn't make any sense is that my CYA went from 90 to 156 without adding any chemicals. I know it can't be the water since On sept 19th I was at 90 and the pool was mainly filled with city water.

Sept 20th
TC 1.8
FC .5
CYA 156
** Pool was 100% filled to winter level
Sept 19th
FC 3.5
TC 1.7
CYA90
** Pool was 70 % refilled to winter level

Sept 18th
TC 6
TC 3.5
CYA 151
** Pool was 70% drained

Any ideas what I should do? My plan is do a shock treatment with bleach so it's ready for next year. However, at this point i'm not sure what my shock value limit should be considering I got a misreading today but I can likely assume it's lower than 90. I don't have a Tf-100 test kit or a taylor as they are very expensive in Canada. Next year I make look at getting one. For now I will use the pool store testing equipment.

Thank you,

 

[domct203]

............... One thing that doesn't make any sense is that my CYA went from 90 to 156 without adding any chemicals. I know it can't be the water since On sept 19th I was at 90 and the pool was mainly filled with city water.

Sept 20th
TC 1.8
FC .5
CYA 156
** Pool was 100% filled to winter level
Sept 19th
FC 3.5
TC 1.7
CYA90
** Pool was 70 % refilled to winter level

Sept 18th
TC 6
TC 3.5
CYA 151
** Pool was 70% drained

Any ideas what I should do? My plan is do a shock treatment with bleach so it's ready for next year. However, at this point i'm not sure what my shock value limit should be considering I got a misreading today but I can likely assume it's lower than 90. I don't have a Tf-100 test kit or a taylor as they are very expensive in Canada. Next year I make look at getting one. For now I will use the pool store testing equipment.

Thank you,

Welcome to the forum.

The best advise I can give you right now is to get your own test kit. Pool $tores have been proven to be an unreliable and inaccurate testing resource. Are you really willing to put your faith in testing that swings 60ppm in three days? You are correct in the assumption that CYA should not go up unless you add it, and adding fresh water should have actually lowered the CYA level.

You really can't effectively SLAM Process the pool on assumptions. The early stages of the SLAM Process will require frequent testing, multiple times during the day. Are you planning to drive to the Pool $tore multiple times in the day for unreliable testing?

Your shock level for the SLAM Process is based on your CYA level. If your CYA is 90ppm, you will need to hold a FC of 36ppm for the duration of the SLAM Process. If the CYA is closer to 150ppm, that would require maintaining a FC of 60ppm, quite impractical.

[FC/CYA][/FC/CYA]

I know that the Taylor K2006C is very expensive in Canada, but to follow a TFP SLAM Process you will need at the minimum a FAS DPD chlorine test, a pH test, and a CYA test.

Your best plan of action is to get a reliable CYA reading, adjust pH and CYA as needed, then SLAM Process the pool.

 

[AftonJeeper]

Have you had a chance to read this? Pool School - Closing an In Ground Pool

I understand your frustration with the pool store, that is how many of us got to TFP. If money is tight wait till next year to get your test kit on order. If you have any friends/family in the US maybe see if you can work out a deal with them to save you some money and headaches next year.

The only algaecide recommended here is Polyquat 60, it doesn't have any copper or other things that will foul up your water and cause other issues. Keep reading through pool school, lots of great info in there. ABCs of Pool Water Chemistry

 

[blueskyup]

Thanks for the advice. I was pretty sure that was the direction i'd be heading. Because my CYA was so high after I refilled the pool I figured that test was incorrect too. I had another test done today and the reading came back even higher:
FC.5
TC1.8
CYA 175

This makes no sense to me. The only thing that changed after we had the test of 90CYA was that I put a clean filter in to do a final vacuum. Is there any explanation for this? Are any of these possibilities?
1. Could the filter still have some trichlor (power chlor) in it from when I did the shock treatments earlier in the season?I had to dispense the power chlor directly through the skimmer and we did end up putting A LOT of power chlor in.
2. The pool lab tech said that maybe there was residue on our liner and when it filled back up it got reintroduced into the water.
3. The pool tech said they have had customers empty their pool 3 times in order to get the CYA down.

our pool supplier uses a testing kit called "ALEX Water Testing" - This is a bio-guard thing.
I have assumed that the test results are correct as they are using this high tech device. Right now I don't have a lot of confidence in it but won't be able to confirm until I get the Kit.
If my Kit confirms the CYA is correct - is that even possible? If you drain the pool the CYA should go down. Is there any explanation why it would go up?

Our pool tech gave me a bottle of CYA reducer bioactive (Not a bioguard product). It claims to reduce CYA without draining pool. She said I can return it if we don't want it. Should I try this?

My plan is to put in the winter chemicals and then start again next season. It would probably take me a week to get my test kit and then I would probably need an additional week to do SLAM. By this time I think it would be too cold and I may risk freezing pipes. Typically we don't get snow until end of October but temperatures can go down to freezing before.

Thanks,

 

[AftonJeeper]

You are correct in thinking the only way to reduce CYA is by draining and refilling. With the vinyl liner you can only do partial drains so it does sometimes take a few to reduce it completely. CYA does also degrade over time, roughly 3-5 ppm per month so that will help you over the winter.

There are only two test kits we are seeing reliable consistent results from, TF-100 and Taylor K-2006C.

So far there have been no reports of the bioactive CYA reducer working. Search for it in the search box at the top of the page, lots of threads, no results.

Your plan is exactly what I would do at this point. Shut her down and make a plan for the spring.

 

[peirek]

Welcome to TFP. The place to fix the Pool Store mistakes.

I suspect the Sept 19th CYA reading was wrong (way low) and the more recent ones are more accurate (since they are close). Have you cleaned your filter to rid it of any shock you added through the skimmer? BTW: Never do this. Always add chemicals at the returns and briefly brush/sweep/mix as necessary. Rule of thumb is at least 15 minutes between different chemical adds. One caveat, adding stabilizer via sock has been used in skimmers as it dissolves in the sock so no granules etc.

 

[blueskyup]

Welcome to TFP. The place to fix the Pool Store mistakes.

I suspect the Sept 19th CYA reading was wrong (way low) and the more recent ones are more accurate (since they are close). Have you cleaned your filter to rid it of any shock you added through the skimmer? BTW: Never do this. Always add chemicals at the returns and briefly brush/sweep/mix as necessary. Rule of thumb is at least 15 minutes between different chemical adds. One caveat, adding stabilizer via sock has been used in skimmers as it dissolves in the sock so no granules etc.

I didn't personally clean my filter but it was done by the pool store. I haven't seen how they do it but from what it looked like before to after was a major difference.

I stil am greatly confused to why my cya didn't lower. Replacing 70% should have done the trick.
next spring I will check the cya and make adjustments as required. However I don't want to empty a large portion of water then be at the same point I am today. Is it possible the filter could have increased cya since I had it cleaned? the other theory is maybe the testing equipment couldn't read a higher cya due to its limitations. But again they say an acceptable range of cya is 30-200ppm. A lot of head scratching.

What do you guys guys recommend I do for spring opening? By then I will have a test kid.

 

[domct203]

The only thing that increases CYA, is adding CYA.

If you drained 70% of the pool, then refilled, your CYA will have been lowered by the same 70%. If you were at 200ppm, you would now be at approx 60ppm.

 

[blueskyup]

I know you have mentioned that the only way of increasing cya is adding it. I haven't added a single thing.


I took the filter out as I assumed it may still have trichlor residual in it. Again, we had the filters cleaned but I'm not sure how clean is clean. Anyways I took another sample in today and our cya went up to 183.

I drained the pool 70%. Refilled it. I Have put in zero chemicals into the pool. My cya went from 151 (prior to refilling) to 90 (50% refilled with new water) to 151 (70% refilled with new water) to 173 then to 184. My FC is .2 and TC is 1.

As the filter is the only thing that was instroduced that must be the culprit. Other than that I have a ghost adding trichlor behind my back.

Does anyone have suggestion that I can do to get the trichlor out of my filters? Alternatively I can look at getting a new one but I know by pool store said they are about $1500. Perhaps I'm completely wrong on my assumption.

I'll share what our pool store has said. There was a residual on the liner so when it was filled up it went back into the water. The worst was the I needed to replace our skimmer box - we haven't even used the skimmer because the pool was drained to winter level.

 

[domct203]

There is most likely no Trichlor in your filter, or undissolved on your liner. Your CYA level is not changing, it’s the unreliable testing that we have been telling you about.

You need to cut the cord to pool $tore testing, and get your own test kit if you plan to be successful with your pool chemistry.

 

[yann]

These are pool store test results.

As you can see they are extremely unreliable.

As previously advised, get your own test kit, either the TF-100 or the Taylor K2006-C and start testing your own water. It's a small cost compared to what the pool stores will sell you to fix problems they created in the first place.
Is it worth driving 2h to the US and get the kit mail dropped?

If your CYA tests at 90+, follow the diluted method explained in step 8 of Pool School - CYA

Then post of full set of results in that format so we can help you:
FC
CC
pH
TA
CH
CYA

In the meantime, stop adding any form of solid chlorine and switch to bleach or liquid chlorine (same thing, different names and concentrations) and add a gallon everyday of the highest concentration you can find (pool store usually have up to 12%) until you can test your own water.

Please add a signature so we don't have to ask the same questions over and over again: Pool School - Read This BEFORE You Post

You are looking at a chemistry problem, not a filter problem.
You'll get great help here if we all speak the same language (test kits)

Good luck

 

[blueskyup]

Thanks for the advice,

today I closed it down for winter. I am worried by the time I ge the kit and go through a round of slam I will be dealing with freezing temperatures. When I open the pool next year I will do what you have advised.

Ill update my my signature as well.