New to TFP, First Pool / High CYA & general questions

[jsridley]

New pool owner since this January. I have been using tabs (tricolor) and powdered cal-hypo “shock” per pool store recommendations until I found this site a couple weeks ago. Got a TF-100 and most recent readings are below:

FC – 5
CC - 0
pH – 7.8 (maybe a bit higher)
TA – 120
CH – 400
CYA – 100 (maybe a bit higher)

I now know that this CYA is high and likely due to previous owner (and myself) using tabs for a long time. I also know I need to raise my FC up to 11-13 to match the CYA level. I’ve been trying to do that over the last week but haven’t kept up with daily FC reduction. Three 121oz. jugs of 8.25% bleach went in this morning.
Been reading a bunch in the forums but still have a couple questions:

- Should I drain and fill to lower CYA to ~50, or just maintain higher FC?
- What’s the downside of maintaining higher FC? Is it just the extra expense needed to initially get it to the higher level? Does more FC mean more chlorine effects from swimming in pool, itchy skin, degrading suits, etc? I believe I understand the “chlorine smell” only really occurs if I have high CC, which would indicate an algea outbreak or the chlorine fighting something, but I’m not sure why if you have high CYA you can’t just keep higher levels of FC and be happy with that.
- What’s the danger of high CH. Is this just a potential issue for the pool equipment? I’ve got some 65% cal-hypo still. Should I definitely not use this due to CH already being at 400?
- When folks talk about testing daily are you doing the quick k1000 test with the colors or the “full” test with the powder. It appears like regardless I need to do the full test due to the FC levels I’m trying to maintain.
- This one is might be a whole thread on its own, but how do so many people get away with shock and tabs. It seems like CYA would just keep getting higher and higher. I have several friends who do this, bring their water to pool store once a month or so and do what they say (which usually isn’t too much, and includes use of Phos-Free every week). I can only think they’re getting lucky. With such a big pool, throwing shock in once a week and keeping tabs in the floaters is clearly much less “trouble” than all this bleach (which also seems like it’s going to be a lot more expensive). Now that I know how the chemistry is supposed to work, I want to do it the right way, but can’t help being just a little skeptical when it seems everyone else does it the “pool store way”.

I’ve got some other questions regarding my pool cleaner setup but will save that for another tread.
Excited to find the forum and very thankful for the help!

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[kellyfair]

Re: New to TFP, First Pool / High CYA & general questions

Once you see your pool the TFP way, you’ll look at all those other pool store pools and realize that their water isn’t nearly as clear and beautiful as yours! Many of them are on a never-ending cycle of running back to the store for a new solution because the previous ones didn’t work. You will know exactly what your pool needs, and it sounds like you are already on the way to that understanding!

You can certainly maintain your pool with a high CYA. But once you get to 100, you need to do the diluted CYA test because it may actually be much higher. And without knowing just what it is, it becomes difficult to impossible to maintain the right FC.

First, I would do the diluted test. Mix pool water with tap water at a 50%-50% ratio. Then test the diluted sample as if it were your pool water. If it comes out as 80, your CYA is somewhere around 160 (the diluted test isn’t exact) and you are really going to want to replace some water.

I don’t know much about plaster pools, so someone else will give you guidance about your CH.

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Oh, and I don’t bother with the quick chlorine test... I always use the FAS-DPD. I want to know exactly how much FC is in my water.

 

[ajw22]

Get a SWG and you do away with tabs or bleach. Well worth the investment.

High FC levels over 10 will make it difficult getting good PH measurements.

With a SWG you need to get your CYA down to 70-80. That would only take about a 25% drain.
With CL you need to get your CYA around 50 and that will take about a 1/2 drain.

If you do regular backwashing and need to add fill water then you can work your CYA down over the season.

Think about adding that SWG.

 

[kellyfair]

Actually, in Texas I would not go as low as 30. I’d shoot for no lower than 50. Gets plenty hot and sunny there!

But yes, SWGs rock!

 

[zea3]

Hi, welcome to TFP! In theory you are right, you can manage a pool with high CYA by keeping the FC at the correct ratio. The problem is FC loss is exponential, not linear. Life happens and you miss a day or two of dosing the pool and it will turn on you pretty quick. In the past I have gone from slightly hazy to full on algae seemingly overnight. To kill off the algae you would need to complete the SLAM Process process, which is more expensive at higher levels of CYA, since the first day or two of the slam goes through a lot of chlorine. Lower CYA levels mean lower FC levels, and lower FC levels are a little more forgiving if you miss a dose or two.

You can manage a pool with high CH levels if you keep the pH low, around 7.0-7.2 and the TA between 70-90. When CH is too high and pH is high scale may develop on the surfaces of your pool, as well as in your equipment. Scale is rough to the touch and can trap algae by providing nooks and crannies for it to grow. Scale will also leave the pool looking dingy and stained.

As for your friends with high CYA who use pucks and powders, they have probably been able to get along for a couple of years by adding algaecides, clarifiers, and flocculants, then at some point they were told they had "chlorine lock" and the only remedy was to drain and refill. So they did and the cycle starts again.

 

[jsridley]

Re: New to TFP, First Pool / High CYA & general questions

I did the diluted test last night. It actually showed around 80 CYA. I re-did a non-diluted test and I'd say it was around 90, so maybe my earlier tests were a bit off. (I'm finding it a bit hard to determine exactly when black dot is gone). Regardless, I'm gonna consider my CYA at 90 for now. It's clear to me that you lose more FC when you maintain above the recommended level for CYA, however it's not clear if that's the case if you maintain within levels. In other words, am I using more bleach to maintain (not get to initially) a recommended FC level at a high CYA vs. a lower CYA. Also not clear if there's any other negative consequences to maintaining higher FC. Water isn't too expensive here so I may just drain/refill.

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ajw22,
I have thought about a SWG, however I've been scared off by reading things like "anything in and around your pool will corrode" I definitely have recently installed metal ladder/railings in the pool and the pool is close by the house so near furniture, outdoor tv, etc. Is the corrosion really an issue?
I've read about people installing pumps for adding chlorine and I question why everyone doesn't switch to SWG... is it just the initial expense? Obviously I need to do some more research into it.

 

[ajw22]

I cant say why more people dont have SWG. I have been a happy owner of SWG pools for over 30years. Seem to be many happy SWG pool owners here.

Question who you are hearing the negatives from? Pool stores who wont sell you as much chemicals once you have a SWG?

Outdoor furniture corrodes because it is outdoors, not because it is near a SWG pool.

 

[kellyfair]

Just checking to make sure the diluted result of 80 was after you multiplied by 2!

 

[jsridley]

kellyfair: yeah, gauge read 40 when diluted... or there about.

ajw22: A quick google search will get you a lot of pages / threads about the "cons" of salt water, corrosion being one of them. Now a bunch of the "cons" I disregard as I mostly understand the chemistry needed to maintain with a SWG, however, I am concerned about the corrosion part, especially after reading that it can cause problems with stone coping around the pool. Again, just need to do some more research, but I appreciate folks like you reporting not having any issues regarding this.

 

[zea3]

Re: New to TFP, First Pool / High CYA & general questions

When evaluating opinions of equipment such as SWGs, look into who is stating the position and what they stand to gain/lose as a result. I see a lot of SWGs are bad articles by companies pushing alternative sanitation methods. Now there are some softer stones that will crumble over time with direct contact with saltwater, so builder's may try to steer you away for that reason, but if you seal the stone annually, or hose it off after a lot of splash out from swimming, its no worse than weathering from being outside.