Newbie Question - FC & CC

mdt0311

Member
Oct 17, 2016
15
Houston, TX
I recently purchased a home with an in ground gunite 10,000 gal chlorine pool. The pool was maintained using pucks prior to purchase and while I was able to keep it good and clean for several months, as soon as I went on vacation I came back to a green pool. I then neglected it for a week or so out of laziness and let it turn into a swamp... I found this excellent website and began reading up to become more knowledgeable on pool chemistry so that I could fix my pool and then maintain it properly moving forward (after getting a $1000 quote from a local pool company to clean it).

After a 2/3 drain and refill to lower my CYA from over 100 to ~40, within a little over a week of SLAMing (I did the best I could... I live further out and work downtown Houston so I am not able to test and adjust levels all day long), my pool was clear again although I did not have the FAS-DPD test at the time so I was unable to do the OCLT to determine if my SLAM was complete. So I continued to add bleach each day while I waited for the k2006 to arrive. Yesterday evening, the test kit arrived and I went out to test my water to find I had an FC of 0 and a CC of 0.5 - this was after adding 2 gallons of 10% liquid chlorine the previous night. So to get to my question - if all of my FC was used up, wouldn't my CC have been much higher than 0.5?

Also for those who are interested, I did get around to doing the OCLT - last night after adding 2 more gallons of 10% liquid chlorine, before bed I was getting an FC reading of 11. This morning, I got a reading of 4 which leads me to believe I still have something growing somewhere in the pool (will post pics later but pool is 100% clear with no visible algae growing) - is it possible the algae is in my cartridge filters? I've made sure to clean them several times throughout the SLAM process but haven't touched them the past 5 days.
 

xyz

Gold Supporter
Sep 8, 2016
641
Escondido/CA
Your suspicions are probably right; You didn't take the SLAM all the way to the end, so the Algae is coming back.

So, now that you have the DPD, make sure you have plenty of Chlorine Reagents. If you don't, get more from

TFTestkits.net

Get plenty of Chlorine, check the table for the proper SLAM levels [you need to know if you have Algae, or Mustard].

Then restart your SLAM.

You are done when:

  • CC is 0.5 or lower;
  • You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
  • And the water is clear.
Pool School - SLAM - Shock Level And Maintain

The reason I know you are not done is that you are using up lots of FC overnight. "using up" is usually from 1) the sun, or 2) killing off of critters. Since there is no sun at night, and you are losing lots of FC, you got critters. If you don't kill em all, and completely, they will come back and back and back.

I'd even suggest you SLAM for an extra day even after you meet the above 3 criteria.

Scrub everything multiple times, and make sure you scrub your light niche(s).

I used a power washer and it worked really well, but don't get too close, some power washers are so powerful they can erode concrete if you get them too close, so plaster will be a breeze. If you are not sure of what I'm saying, or you are not very confident in this, ignore this suggestion, and stick with brushing every square inch of your pool multiple times.

And then wait ANOTHER day, and do ANOTHER OCLT. Keep plenty of chlorine on hand, and plenty of chlorine reagents.

Some people have taken multiple weeks to clear up their pool (although you don't seem like you are in too bad a shape).
 

mdt0311

Member
Oct 17, 2016
15
Houston, TX
Your suspicions are probably right; You didn't take the SLAM all the way to the end, so the Algae is coming back.

So, now that you have the DPD, make sure you have plenty of Chlorine Reagents. If you don't, get more from

TFTestkits.net

Get plenty of Chlorine, check the table for the proper SLAM levels [you need to know if you have Algae, or Mustard].

Then restart your SLAM.

You are done when:

  • CC is 0.5 or lower;
  • You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
  • And the water is clear.
Pool School - SLAM - Shock Level And Maintain

The reason I know you are not done is that you are using up lots of FC overnight. "using up" is usually from 1) the sun, or 2) killing off of critters. Since there is no sun at night, and you are losing lots of FC, you got critters. If you don't kill em all, and completely, they will come back and back and back.

I'd even suggest you SLAM for an extra day even after you meet the above 3 criteria.

Scrub everything multiple times, and make sure you scrub your light niche(s).

I used a power washer and it worked really well, but don't get too close, some power washers are so powerful they can erode concrete if you get them too close, so plaster will be a breeze. If you are not sure of what I'm saying, or you are not very confident in this, ignore this suggestion, and stick with brushing every square inch of your pool multiple times.

And then wait ANOTHER day, and do ANOTHER OCLT. Keep plenty of chlorine on hand, and plenty of chlorine reagents.

Some people have taken multiple weeks to clear up their pool (although you don't seem like you are in too bad a shape).

Thank you for your advice and words of encouragement. I already actually ordered more of the DPD powder and R-0871 reagent from TFTK to ensure I have plenty to finish out my SLAM with and I also picked up a ton of bleach from my local Walmart.

When I started the SLAM, I didn't realize my leslie's test kit wasn't FAS-DPD so while it was more accurate than strips, I still could not get granular enough to determine my true FC loss. I will take this advice and follow the SLAM to the best of my ability and post progress as I go along.

Also, i'll post a full list of my chemical levels this evening if that helps paint the picture.

Thanks, again!
 

MarianParoo

Well-known member
Aug 16, 2014
4,615
Northern IL
Busy watching the Cubs, I mean World Series...

Just quickly, look on the inner lid of your test kit for directions on how to use the 10ml water sample size for FC/CC. And no, using up FC will not result in an equal CC reading. Back to the game!
 

mdt0311

Member
Oct 17, 2016
15
Houston, TX
That was a great game! Thanks for the info.

Going to take out the filters this evening and give them a good cleaning. This weekend I plan to take the light out and see what may be growing behind it - the top screw is in, but it appears to be sliding off it's spot a bit and exposing a small entrance to behind the canister - the light itself hasn't been functional since I bought the place, but we don't really swim at night much anyways.

Saw another ~7ppm FC loss overnight again. Hoping cleaning the filters again and behind the light will put me closer to the end of the SLAM.

Is there any chance the dead white algae on the bottom of the pool could be causing me issues? I've run my automatic vacuum several times but it doesn't seem to vacuum much of it up - just stirs it around. I don't have a manual vacuum at this time - would it be more effective for me to purchase and use one of those instead?
 

xyz

Gold Supporter
Sep 8, 2016
641
Escondido/CA
That was a great game! Thanks for the info.

Going to take out the filters this evening and give them a good cleaning. This weekend I plan to take the light out and see what may be growing behind it - the top screw is in, but it appears to be sliding off it's spot a bit and exposing a small entrance to behind the canister - the light itself hasn't been functional since I bought the place, but we don't really swim at night much anyways.

Saw another ~7ppm FC loss overnight again. Hoping cleaning the filters again and behind the light will put me closer to the end of the SLAM.

Is there any chance the dead white algae on the bottom of the pool could be causing me issues? I've run my automatic vacuum several times but it doesn't seem to vacuum much of it up - just stirs it around. I don't have a manual vacuum at this time - would it be more effective for me to purchase and use one of those instead?

FC kills algae, not scrubbing, not filters, and not cleaning behind the light. The scrubbing and cleaning behind the light is to make sure you get every last critter *exposed* to the FC. Some Algae form a colony, and the algae on the top layer gets killed, but then protects the algae under that. Once the FC goes away, they can grow again. So scrubbing is to make sure every last organism gets direct exposure to the FC. THEN they will all be gone.

With 7 FC overnight, that means you have plenty of road ahead before you are done.

If it were me, I would get vacuum attachment. Handy for when there is a storm, or exceptional situations. They are not that costly, and don't take that much time to use. If your system supports it, you could also vacuum to waste so you are not clogging up your filter as quickly [although this means you will have to add water]. It will also be easier to meet one of the 3 requirements necessary to declare your SLAM complete -- crystal clear water.
 

pabeader

LifeTime Supporter
TFP Guide
May 14, 2015
4,349
Cartersville Ga
At this point it would be a good idea if you would update your signature with ALL the stuff you have. That way we can see if there is something on the list that warrants further info.

Also, brushing at least once a day is very important.

Note: We love pics around here. Post pics of everything. Cleaner, filter, equipment pad, stairs in pool... You get the idea. :)
 

mdt0311

Member
Oct 17, 2016
15
Houston, TX
Sorry I went kind of dormant. I've updated my sig with everything I have.

A bit of an update:

When I went in to clean the filters 2 weekends ago, I realized the current filters had broken bands etc. - so I replaced them with what's outlined in my sig. My pool is 100% clear/clean. I am scrubbing once per day and adding bleach as necessary and manually vacuuming as much as possible. I am still seeing a decent OCL (roughly 4PPM) and the only thing that has not been cleaned yet is behind my pool light. Could this really be causing the last of my issues? Even if there is an algae bloom back there, shouldn't such a small amount equate to less chlorine loss than I am experiencing overnight?
 

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jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
I would not think that algae behind the light (which may or may not exist) would be causing a 4ppm overnight drop.

Any sun exposure between your OCLT tests?
 

mdt0311

Member
Oct 17, 2016
15
Houston, TX
I would not think that algae behind the light (which may or may not exist) would be causing a 4ppm overnight drop.

Any sun exposure between your OCLT tests?

My pool ended up turning to a pretty thick swamp before I got it to where it is so i'm guessing something is back there.

I have not had any sun exposure during my OCLT attempts. My last OCLT was Saturday night to Sunday morning, but when that failed again I decided that maybe the issue was that the pipes leading to my waterfall have not had any water pumped through them this whole process as I haven't been running the feature. So I have kept my pool at SLAM level the last few days with pump and water feature running 24/7 - I brushed the rock waterfall a little each night.

Guess it wouldn't hurt to try another OCLT tonight but I'm loosing faith in myself to complete this SLAM.
 
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