Starting over after power outage-- No Chlorine or CYA

[Andyhl2]

After having crystal clear, beautiful pool water for the last month or two, we lost power on June 29 and were without power for a week. During that time the swimming pool not only was very dirty with leaves and other debris in the deep end of the pool, but it went from clear to cloudy. When power was restored on Friday night, I immediately began adding chlorine.

While the water has cleared up, it is not perfect, and the bigger issue is that it will not hold chlorine. I add lots of chlorine (bleach) at night and it is essentially gone by the morning. This pattern has held for the past few days. I have read your guide on pool openings and see this is a common problem at start up but I am trying to figure out how I break out of this. When I last tested for CYA a couple of days ago, I did not have any. I added four pounds soon after the power came on to go along with the chlorine, but I know will need to add more eventually but I am not sure when. Also, I have an automatic cover which I have been leaving off and a salt water generator. The pool is 28,000 gallons. These are my before and after numbers:

Before loss of power:

FC: 5
CC: 0
Alk: 125
pH: 7.6
Calc: 200
CYA: 35
Borates: 35

After loss of power:

FC: 0
CC: 0
Alk: 140
pH: 7.5
Calc: 190
CYA: 0
Borates: 35

I am not sure what to do next. I have 5 1/2 gallons of more bleach that I am going to add tonight, which is about twice the amount I have been adding. I also bought 8 pounds of cya but I am not sure when to add it. I take it that I should leave my cover of, is that correct? On the other hand when I leave the cover on, the chlorine levels rise, but I am thinking at these high levels of chlorine I should keep the cover off. Any other suggestions? This is very frustrating. Thanks.

[PoolDoc]

It sounds like slime (algae + bacteria) have biodegraded your CYA to ammonia. We seen this more this season, than in the 14 years previous. I would have never guessed it could happen in only a week!

Use this chlorine demand bucket test to verify the problem: http://www.poolforum.com/pf2/showthread.php?16973 The only practical method for removing lots of ammonia formed during the biodegradation of CYA is LOTS of chlorine.

Mean while, add your bleach every night, till you've either (a) solved the problem or (b) found another solution. And, turn off your SWCG if it's still on -- you'll just wear it out.

[Andyhl2]

Thanks for the response. Does that mean I should not add CYA yet? If so, when should I add it? Thanks.

[PoolDoc]

Do the demand test first.

If you have lost your CYA to ammonia, you will want to raise your pH some, and begin adding large doses of bleach in the late evening. We don't want to add MORE stabilizer, till we can be pretty sure the stabilizer eating slime is all gone!

[chem geek]

It can happen very quickly. I had this happen to me during one spring opening a few years ago and it took less than one week -- probably 3-4 days. My CYA went from around 30 ppm to close to zero, the pool turned cloudy, and I had a huge chlorine demand from ammonia and partial CYA products (probably biurate and allophanate) that came from bacterial biodegradation of CYA. A log of my chlorine usage to clear the pool is in this post. A technical explanation of the biodegradation of CYA is in this post.

Note that I had to add a LOT of chlorine and that it got consumed very quickly early on, so add it multiple times during the day measuring until the chlorine starts to hold. Once you get an FC reading that is mostly stable (i.e. not dropping to zero in hours), then you'll know that you've killed off the bacteria because they can't survive when FC is present. It's at that point that you can start to add some CYA to the water, but not too much (say, not more than 30 ppm) until you lose < 1 ppm FC overnight.

[Andyhl2]

Thanks for the responses. Pool Doc, I will hold off on the cya. Unfortunately, based on Chem Geek's experience, it may be a while before i add it. Chem geek, that is one very scary chart you have there. I am not looking forward to going through what you went through. It looks like I am going to need a truck load of bleach. Ugh.

[Watermom]

Not that it will help you now, but just reference in case you are ever in this situation again.

I, too, lost power on June 29 and it did not come back on until the evening of July 6. My solar cover blew off the pool and there were branches, twigs, leaves ,dirt all in the pool. I cleaned out as much debris as I could by hand but of course, could not get the dirt and bits of leaves out without a working pump as you noted above. However, we swam every day. We had to to stay cool as the daytime temps were over 100 and the temp inside my house was in the 90s. The bottom of the pool was dirty but the water was clean and clear. Every evening before I got out of the pool, I slowly walked all over the pool drizzling in a jug of bleach and then using arms and body to create lots of splashing and water movement to get the bleach mixed in. I did this each of the night while we had no power. In this way, I was able to keep the pool from turning into a green slime pit and in 100+ degree weather like we have been having, it wouldn't take long for that to happen!

Sorry you are dealing with this. If it ever happens again, you will know better what to do.

[Andyhl2]

It looks like I am on the right track. After getting no or very low chlorine readings in the morning for the past several days, I finally had a 6.5 fc reading this morning. Watermom, I hope it doesn't happen again, but if it does, I will definitely be following your technique. I thought about doing it, and in retrospect I should have, but I guess each day we kept thinking that this would be the day that power comes back. Thanks for the advice.