Cannot maintain any FC

[zuckerem]

We recently bought a home with a 6,800 gallon fiberglass pool in New Jersey which is in direct sunlight during daylight hours.

The previous owner was maintaining a chlorine tablet in the skimmer (using Pool Life’s MPT Extra tablets which is basically 93.5% Trichlor) and shocking weekly with Cal-Hypo.

Pool water is very clear but could never get a FC reading other than 0.

When I first took ownership, I went to the pool store where I was advised I had extremely high phosphates and that’s why I had no FC. After weeks of phosphate remover treatment and getting nowhere, I begun my own research and discovered TFP.

I just purchased my TF-100 kit and ran the tests. I also did an overnight chlorine loss test.

The results were:
FC: .5
PH: 7.5
TA: 140
CH:425
CYA: 85

Overnight chlorine loss test:
Started at 3ppm.
next morning level maintained at 3ppm.

By end of day, the level dropped close to 0 again.

As a result, I ruled out existing algae as the likely issue and am thinking it is the small pool being exposed to so much sunlight. Additionally, this problem is being compounded by the CYA being so high. Would you agree with my assessment or think something else might be going on?

If my assessment seems to be correct, would the recommendation then be to drain/refill the pool ~40% and try to get a lower CYA level thinking that will help maintain a good FC level?

Please note, I haven’t transition to TFP’s recommendations yet of using bleach, etc. because I was trying to just maintain what the previous owner was doing initially so i could figure out what is the current situation and determine how best to move forward.

Thanks for the advise!
Eric

 

[ajw22]

The chlorine tablets are raising your CYA while the cal-hypo shock is raising your CH both to what will soon become unmanageable levels. You should stop using them immediately and switch to bleach for your FC.

There is no reason to shock your pool weekly. Just maintain the proper FC levels. Your problem is that with a CYA of 90 your FC target should be 10 - 12. See this chart --> [FC/CYA][/FC/CYA]

For a non-swg pool a CYA of 30 - 50 is more manageable.

BTW, you can't eyeball the CYA measurement and say it is 85. The CYA tube scale is logarithmic and not linear. You round up to the next marking.

Use PoolMath to determine the amount of bleach to be added and drain about 50% of your pool to get your CYA down. Let's see what FC level you can maintain using bleach.

If you get to a CYA of 40 your target FC is 5 - 7 and your minimum you should always have is 3.

Your other option is install a SWG. You already have your CYA up to SWG levels. A SWG eliminates the constant adding of bleach to keep your FC up.

 

[mknauss]

Welcome to the forum!

Raise your FC to target level based on [FC/CYA][/FC/CYA] with liquid chlorine. Your 3 ppm loss you showed in your post is normal for a summer day. So you need to have a higher starting point of FC.

You should exchange some water. A fiberglass pool in most cases should never be drained more than a foot or so as they can pop out of the ground.

Review this if you plan to exchange water -

You can exchange some water without draining.

If you place a low volume sub pump in the deep end and pull water from there while adding water in the shallow end you can do a fairly efficient exchange. That is assuming the water you are filling with is the same temperature or warmer than your pool water. If your fill water is much cooler than your pool water, then switch it. Add the water to the deep end (hose on bottom) and pull water from the top step.

The location of the pump and fill hose may change if you have salt water, high calcium, etc.
In my pool, with saltwater and high calcium when I drain, I put the pump in the deep end and hose in shallow end. The water in the pool weighs more per unit volume than the fill water from the hose.

Be sure to balance the water out and water in so the pool level stays the same. Also be sure your pool pump is disabled during this process. Once started do not stop until you have exchanged the amount of water you wish.

 

[zuckerem]

Thank you both. This is extremely helpful and interesting about the sub pump method to exchange water.

The SWG idea is interesting because the previous owner had a SWG system set up, but said he was having trouble with it because he bought one from a manufacturer that went out of business and finally gave up on it. As a result, for years he has not been using it and just doing the weekly shock and chlorine tablets. Do you think if I had the SWG replaced, it would work effectively with the +1000 phosphate levels I apparently have and high sunlight exposure?

 

[mknauss]

SWCG could care less about phosphate levels. TFPC in general could care less about those levels.

I have a SWCG in the Nevada desert, I get WAY more intense sun than you do. Just be sure any SWCG you get is sized for a minimum of twice your pool size. I went crazy and got one 6 times! Works great ------

 

[zuckerem]

Got it- any specific brand you would recommend?

 

[mknauss]

Depends. You do not show pump type or if you have automation. A more complete signature would be very helpful.

So, for a standalone SWCG (no automation) Circupool and InyoPools in house brand, CrystalPure are acceptable.

For automation systems, you need a SWCG from the same manufacturer as your pump and automation.

I would not get a unit sized under 20K gallons for your pool.

 

[ajw22]

I have a Pentair Intellichlor IntelliChlor - Pool and Spa Sanitizers - Pentair

Are you going to install it yourself or have a pool company do it?

 

[zuckerem]

Got it. I will check the specifics on what I currently have set up and will adjust my signature.

ajw22- I would need assistance with any install. I see you are in Northern Jersey as well. Any company you recommend for such jobs?

 

[ajw22]

ajw22- I would need assistance with any install. I see you are in Northern Jersey as well. Any company you recommend for such jobs?

I PM'd you with who I use.

Pool companies usually install the major brands - Pentair, Hayward, Jandy. So you either take the brands they install or you need to shop for an installer who will put in the brand you want.

A good installer will help you select the brand that best works with your equipment. But tell them you will pay a few dollars more for an oversized cell.

 

[zuckerem]

So.... sorry for the late update but I got a Pentair IChlor 30 bundle SWG installed and still seem to be struggling to get enough FC! Even after running at 100% for 24 hours, the FC level was only at .5.

Here are my other test results:

[FONT=&quot]Chlorine: .5[/FONT]
[FONT=&quot]CC: 1[/FONT]
[FONT=&quot]TC: 1.5[/FONT]
[FONT=&quot]
[/FONT]
[FONT=&quot]TA: 80[/FONT]
[FONT=&quot]CH: 425[/FONT]
[FONT=&quot]PH: 7.5[/FONT]
[FONT=&quot]CYA: 70

Thoughts?[/FONT]

 

[mknauss]

The only way that can occur is that you have algae in your pool consuming the FC.

Do a Overnight Chlorine Loss Test and review the SLAM Process process.

 

[ajw22]

CC of 1 indicates you may have picked up some algae in the water that is consuming your chlorine . Follow the SLAM Process process and get your CC down to 0 - .5. After the SLAM Process turn on your SWG when your FC is around 6 and it should hold it or raise it.

 

[PoolguyinCT]

So.... sorry for the late update but I got a Pentair IChlor 30 bundle SWG installed and still seem to be struggling to get enough FC! Even after running at 100% for 24 hours, the FC level was only at .5.

Here are my other test results:

[FONT=&quot]Chlorine: .5[/FONT]
[FONT=&quot]CC: 1[/FONT]
[FONT=&quot]TC: 1.5[/FONT]
[FONT=&quot]
[/FONT]
[FONT=&quot]TA: 80[/FONT]
[FONT=&quot]CH: 425[/FONT]
[FONT=&quot]PH: 7.5[/FONT]
[FONT=&quot]CYA: 70

Thoughts?[/FONT]

Ichlor is a great unit.. I installed about a half dozen this year, largest pool was 18 it 19k gallons.

Such a small pool in the northeast, seasonal displacement is quite significant.

How much salt have you added?