Algae in pool

[ohaya]

We've had our pool (28000 gallon, concrete/plaster) for quite awhile, and this year, for the first time, we are having problems with algae (mainly on walls on deep end, near skimmer).

We've had a lot of rain this year, and it's also been really hot. I don't know if that is why.

Anyway, I have been reading and if I am understanding, I should test CYA first (I do have a Taylor test kit). Is that correct?

Please advise.

Jim

 

[mknauss]

A full set of test results is best. You should be monitoring CYA level at least monthly during swim season.

 

[ohaya]

Hi,

Yes, I know. Things have been crazy here - all kinds of crazy, work and other stuff.

Earlier (a couple of weeks? or maybe a month) I had algae first time, and found there was like 0 CYA, and had to add bunch of stuff (don't remember) to get the CYA up > 0, then it was good for awhile and then I got busy and missed testing and I think the CYA is high now - I will do some tests (for CYA and FC) and post here.

 

[ohaya]

Hi,

BTW, if the CYA is too high (>100) is the only way to drop it really to drain water from the pool?

 

[mknauss]

BTW, if the CYA is too high (>100) is the only way to drop it really to drain water from the pool?

Correct.

 

[ohaya]

Bummer - just found that I am out of the R-0013 reagent. Ordering some from prime for delivery tomorrow.

 

[ohaya]

Correct.

Ok, thanks!

 

[ohaya]

Only test I was able to do was the FC one - 25ml - 42drops so I think FC is 42x0.2=8.4.
I'll try the test again tomorrow after the CYA reagent gets here.

 

[Rancho Cost-a-Lotta]

For the FC/CC test, using a 10 ml sample will save your reagents. Each drop is valued at 0.5 instead of 0.2. A 10 ml sample will still provide you with enough accuracy. I hate to admit it, but I just completed a SLAM due to what I believe was mustard algae. I guess it happens to the best of us (and me too). With a CYA of 80, I had to maintain FC at 31 initially, then 44 ppm for 24 hours (at temps of over 100 degrees). During the SLAM, I used a 5 ml sample for FC/CC tests. Each drop counts as 1.0 using the 5 ml sample.

Best of luck on the SLAM.

 

[ohaya]

For the FC/CC test, using a 10 ml sample will save your reagents. Each drop is valued at 0.5 instead of 0.2. A 10 ml sample will still provide you with enough accuracy. I hate to admit it, but I just completed a SLAM due to what I believe was mustard algae. I guess it happens to the best of us (and me too). With a CYA of 80, I had to maintain FC at 31 initially, then 44 ppm for 24 hours (at temps of over 100 degrees). During the SLAM, I used a 5 ml sample for FC/CC tests. Each drop counts as 1.0 using the 5 ml sample.

Best of luck on the SLAM.

Thanks for that. I was using the 25ml because I was assuming that the 10ml sample wouldn't be accurate enough.

 

[ohaya]

Hi,

Got the new R-0013 reagent (from Amazon) yesterday.

CYA: >100 (K2006 kit tube doesn't have lines for >100)
FC: 10.5 (10ml sample/.5 per drop, 21 drops)

One of my sons came over and brushed the pool 2 days yesterday. Algae seems mostly gone, but there was some staining in the spa seat).

Pool is 28000 gallons.

We had a lot of rain day before yesterday, so I already drained about 1.5 tiles worth of water).

How much SHOULD I drain?

Also, it has been super hot here so I have been told it is not good to drain (the pool concrete/plaster) a lot when it is hot, so what is the best thing, other than draining, that I can do to try to keep the pool algae away until we close (scheduled for end of September, today is 8/20)?

 

[mknauss]

CYA: >100 (K2006 kit tube doesn't have lines for >100)

Follow Step 8 in CYA - Cyanuric Acid Test - Trouble Free Pool

 

[ohaya]

Follow Step 8 in CYA - Cyanuric Acid Test - Trouble Free Pool

Hi,

I ran that diluted test (step 8) and it just barely still made it to only the 100 mark, so I'd say CYA is 100x2 = 200?

Also, that was after I had drained about 1 1/2 tiles (height) of water from the pool yesterday (we had ran the day before that).

So I still kind of have the question above. We are close to closing (about 1.5 months. Weather seems to be getting cooler...today was about 80. But/so should I still drain water out of the pool, and how much (pool is 28K gallons)?

 

[mknauss]

With that level of CYA, pretty much need to replace the entire pool volume.

Draining entails risk. Do you have nearby surface water?

It is either limp along until you close, then you will close with algae in the pool and sky high CYA. That is a recipe for ammonia come the spring. Which would then be best to drain and start fresh.

If you decide it is safe for you to drain, I assume you have a good source of fill water. No iron?
Home Depot rents sump pumps that will drain the pool in about 6 hours or so. You do need a place to send that kind of flow of water.

 

[ohaya]

is it possible/feasible to drain the pool incrementally, i.e., a foot at a time, then fill a foot, then drain another foot. I really don't want to drain the entire pool at one time and risk it popping.

Jim

 

[mknauss]

You can, but the amount of water needed will skyrocket. Is your water free?

 

[ohaya]

You can, but the amount of water needed will skyrocket. Is your water free?

No our water is not free (we get it from the county water authority).

 

[ohaya]

Hi,

We are still having algae, maybe 2-3 days after brushing (each time). I am still unclear about draining incrementally. We have about a month until we close, so can I do that (e.g., drain 1-2 feet at a time, then re-fill and test CYA)?

Jim

 

[ohaya]

Also, it is still hot here (~95 F), so if I drop the water 1-2 feet, some of the plaster will be exposed. Is that ok? Or will it potentially damage the plaster while we fill the pool back up?

Sorry that I seem to be being obstinate, but we are really hesitant to drain it completely.

Thanks,
Jim

 

[Rancho Cost-a-Lotta]

You can calculate the amount of water you drain if you know (or can estimate) the surface area of your pool. Each cubic foot of water equals 7.48 gallons. For example, my pool's surface area is about 540 sq. ft. To calculate, I multiply 540 by 7.48. Each foot I drain removes 4,039 gallons. Divide that number by the volume of the pool (4,039/18,375=.22 or 22%) to arrive at the percentage of total volume drained, which is equal to the reduction of CYA. So, for each foot I drain, CYA level drops by 22%. Try to exchange water in the early morning or evening if possible. If doing it during the day, splash water on the plaster or use a hose to keep it moist.