CYA and CH both decreased...

[Dreampool13]

Hello,

I've been back of the swing of things and performing complete pool chem tests with my TF-100 kit after a long winter of only testing chlorine and pH. When I first tested on March 6, here were my results:

3-6-2014:

FC 8.0
CC 0.0
TC 8.0
pH 8.0
CH 730
CYA 90
TA 110

I've adjusted pH and chlorine as needed but I haven't tested cya or CH since. The other day I ran another full test and here's what I got:

4-14-2014

FC 7.0
CC 0.0
TC 7.0
pH 7.4
TA 100
CH 500
CYA 70

What would cause big drops of CYA and CH over the course of a month? It has been raining and we've been swimming so there has been some splash out, but not enough for huge drops in those numbers. I'm kind if relieved because now I don't have to drain. I'm in hot Houston with full sun so CYA of 70 works well got me. I'm really concerned that I have a leak though. The pump looks fine and there is no water leaking at the pumps. Where else do I check for leaks? I do feel like I've needed to add extra water here and there but nothing substantial. Maybe and inch of water to keep it at appropriate levels.

Should I just count my blessings or does this look like a problem? My pool warranty is up in June so Ud like to figure this out while the pool builder is still responsible. Has this ever happened to anyone before?

 

[JasonLion]

Do you have an overflow drain? If so it would be fairly easy for there to have been more rain than you might have been aware of and enough water replacement to make a significant difference.

 

[Dreampool13]

I do have an overflow drain and it's a possibility. According to the pool calc, I would need to drain 22% of my water to drop 20 points of CYA And that is 3,700 gallons. I can't imagine that much would drain away but I guess it's possible.

When we built the pool, there was an area of gunite by the steps that always weeped water into the pool, but I doubt that water could drain out of that area after the luna quartz was sprayed on.

 

[jblizzle]

How much rain have you gotten? 22% would likely be around 10" (maybe less if your pool is deep)

 

[Isaac-1]

Judging by the rainfall here in SW Louisiana the last 6 weeks, I suspect houston is close to 10 inches in that time period, depending on exact location. Keep in mind this part of the gulf coast averages around 54-60 inches of rain per year.

 

[Dreampool13]

Thanks all! This is good news to me. I have been waiting to get paid so I can rent a pump and buy a backwash hose, but fortunately I don't need to anymore. My pool was built in June of last year so I haven't been through a rainy spring as a pool owner yet.