Need help with indoor pool

[javo3pp]

Hi everyone.
I have a big issue with the water quality of an indoor pool. Water last clear for only 2 or 3 days after doing a shock, and doesn't look that clear after doing a backwash. Chemical are in good level and I've been trying everything to solve this issue. I've take out some sand and a new one, replaced the air relief connectors. I've done all this because I thought there was a problem with the filter pressure because after a backwash the pressure at filter 1 is 22 and filter 2 is 20, and that is not right because it has to be in at range of 8 psi to 15 psi (according to the manufacturer). I really don't know what else to do. The following are some specifications of the pool . If according one can help me, I will really appreciate it.

Pool rectangular 59ftx19ftx4ft (Plaster)
Water capacity 33,630
FC 2.5
PH 7.6
CH 250
Al 100
Temp 82
2 triton II TR100 sand filters

Readings after a backwash
Filter #1 22 psi
Filter #2 20 psi
Flow meter 250
Water clarity 60%

Reading one week after backwash
Filter #1 24 psi
Filter #2 22 psi
Flow meter 225
Water clarity 40%

Reading two weeks after backwash
Filter #1 25 Psi
Filter #2 23 psi
Flow meter 220
Water clarity 30%

After the pool has been shocked the water clarity is 80% but it last for only 3 days.

Can Anyone Help me.

Thanks

 

[JohnT]

Welcome to TFP!

What are you using to chlorinate, and what level of FC do you maintain? How is the chlorine added?

The fact that "shocking" the pool clears it would seem to indicate that the problem is a lack of sufficient chlorine for the bather load. I think you will find that if you follow the guidance in the Pool School article SLAMing Your Pool that the water will clear.

Filter pressure is determined by many things. Dirt in the filter, pool plumbing and pump size are the main contributors. Every pool is different. The fact that your pressure is rising indicates a pretty heavy bather load since you don't get debris or algae like an outdoor pool does.

 

[javo3pp]

Hi John

I'm using sodium hypochlorite 12%, and I maintain the FC at 2.5. The Chlorine Is Addis By The Feeder CAT 4000. And in fact the bather load is high, probably 250 per day.

So the pressure on the filters has nothing to do with the clarity of the water.

Is normal that sand on the filter gets hard. Yesterday I was trying to remove some sand in filter #1 the sand was smooth but in filter #2 was really hard and almost at the bottom it was black and smelly.

Thanks

 

[jblizzle]

What is your CYA level? That determines the required FC level to maintain a clear pool.

How do you "shock" the pool? With what product?

 

[javo3pp]

Jblizzle

The CYA level is 50. That means that I have to keep the FC at 6ppm. I will increase it to see what happens.

Thanks

 

[jblizzle]

Cloudy water is generally a chemistry problem. And now it is clear that you have not been maintaining the FC level high enough so something has started to grow. You may in fact need to follow the ShockLevelAndMAINTAIN Process to eradicate what is in the water now.

 

[javo3pp]

Ok thanks . I will Slam and see what happens.. thanks

 

[singingpond]

Where is the pool located? Just curious about regulations that may influence what you are allowed to do in terms of chemistry (sounds rather like a public pool, with that many swimmers).

And why a CYA level of 50 for an indoor pool? If CYA were lower, your required chlorine levels would also be lower, both for maintenance and for SLAM process.

 

[javo3pp]

Singingpond

The pool is located in Queens NY, we open an small gym with a pool. I took the clases to become a CPO but they are very briefly when it comes to all that issues. I never thought that the CYA levels affects the quality of the water.

 

[jblizzle]

That is one of the MAJOR pieces of information that the CPO training gets wrong. Check this out for more information: http://www.troublefreepool.com/thre...ol-Operator-(CPO)-training-What-is-not-taught

 

[singingpond]

I was under the impression that New York State doesn't allow any CYA in public pools. Maybe that is incorrect, or maybe this doesn't count as a public pool for some reason?

On a more practical note, how sure are you of the CYA number -- how was it measured?

 

[javo3pp]

Singingpond

It was measure using Lamotte DPD test kit

 

[singingpond]

I was reading a little about Lamotte test kits -- they mention an FAS/DPD kit which also includes a number of other tests, including CYA test. The CYA test is described as being done by dissolving a tablet in a sample of pool water, and then doing a disappearing dot test -- is that what you did to get your CYA number? And are you using an FAS/DPD test for chlorine (the test where you first add powder to the water, and then add a liquid reagent, drop by drop until pink color disappears)? Or is it a DPD test (liquids only)?

Regarding your filters, you may want to read this tutorial on deep cleaning a sand filter, in case that is a process you aren't familiar with:
http://www.troublefreepool.com/threads/73192-Deep-Cleaning-a-Sand-Filter

I'm still wondering why you have those CYA levels (i.e. is it an intentional part of your maintenance of the pool, or is it just something that's already in the water and you haven't given it much thought)?

I have no experience and little knowledge with regard to large public pools, so I hesitate to give much advice. Hopefully others, with more knowledge of the issues, will chime in.

I would not wish to swim in this pool, with the water chemistry and appearance you describe, and with that many people sharing germs, etc. in there. If the CYA is indeed 50 ppm, then your normal FC levels (at 2.5) are inadequate for good sanitation.