Seawater POOL!!

[badtunes]

Hi Guys

I have just started looking after a pool. It is 100,000 litres, tiled and has a 2hp pump running a 36inch filter with a swg (aquablue)

Problem is the guy uses a seawater well to fill it with.

The Pool had not run since october and was a mess.

I have got it clean now and turned on the swg and it does not seem too bad

levels are
ph 7.4
alk 108
calcium hardness 387
cya 38
oh and salt lots!!!

Obviously his equpment is gonna get wrecked, but does anyone have any advice they could give me ref running this setup. I have the swg on 100% but it does not seem to be maintaing levels at all, it does have the high salt indicator on.

Many regards


Andy

 

[JasonLion]

Very high salt levels are not a problem if the pool is built with the correct materials. Copper heat exchange coils are out, and many SWGs won't work, but other brands of SWG will work and all of the common pool finishes (plaster, vinyl, fiberglass) are alright. You also have to be careful about what kinds of metal you use if the metal touches the water, and many kinds of natural stone will have problems.

SWGs are designed to run at much higher CYA levels. After ruling out any chance of algae, you should raise the CYA level up to the 70-80 range. There is a great article in Pool School about water balance for SWGs, well worth reading.

 

[Melt In The Sun]

Was this run as a freshwater pool before? You say the high salt light is on, which suggests to me that it was. If that's the case, he needs trucked-in fresh water.

 

[badtunes]

No, he tells me the pool is three years old and he ha always used the seawater, this i can believe as it is starting to get deposits of salt all over the walls etc

chers for any help

 

[Strannik]

can you quantify 'lots of salt'? and also is salinity of his pool the same as the water he uses to refill?

 

[Poolschoolgrad]

Andy

I was surprised to learn that these units can operate at higher salinity concentration than we normally see here in the US. These units will work at higher salt concentrations, however, only at reduced chlorine output levels.
Sea water salinity of 35,000 ppm would not work, but if the well water is a mixture of mostly fresh water with some sea water, then it could work.

How much salt is "lots"?
Can you have the salinity tested at the pool shop? Drop based salt test kit? or the very least some salt test strips?

Here is the Data Sheet for the AquaBlue:
http://www.pmp-tec.com/pdf/AquaBlue%20Datasheet.pdf

From the owners manual:

A solid red light indicates high salt:
"Operation at very high levels (i.e. above 5500ppm) is not
recommended. Slowly turn down the Control Knob until the desired
green light illuminates (i.e. desired chlorine production level)"

Flashing Red Light - above the Power Meter indicates that the salt level
in the pool is extremely high (i.e. above 7000 ppm), and should be
reduced by draining a significant amount of pool water and refilling the
pool.

Here is a link to the owners manual.

http://www.pmp-tec.com/pdf/AQUABLUE_ENGLISH_PSC_3.pdf

With Calcium almost 400, scale build up inside the cell is very likely.
Scale build up inside the cell will reduce chlorine output.
See page 14 for proper cell maintenance.

-------------------------------------------------------------------------------------

The salt water chlorine generators can maintain chlorine level; however, if there is any algae remaining in the water, the unit cannot produce enough chlorine to keep up.

If the water is clear then try adding 2 of the 3.6 liter jugs of 6% bleach to increase the Free Chlorine level to 4 ppm.

http://www.poolcalculator.com/

* This is the first time I have used the pool calculator in Metric mode


With proper salinity, a clean cell, and a little boost of chlorine, you should be able to get this pool under control.

Please keep us updated with your progress

PSG

 

[badtunes]

Salt is 33,000 ppm

 

[Strannik]

if those units are not time based, but load based you could try setting SWG at the absolute possible minimum. if that gets around high salt alarm (which i doubt) it should work ok. otherwise you'd have to either dilute it with fresh water, or get a unit which is designed to work with seawater

 

[MajorDIYer]

Unlike a traditional pool with SWCG where fresh water is always added, wouldn't the concentration of salt constantly increase in a pool like this as water evaporated (leaving the salt behind) and more seawater was put in? I would think to maintain a reasonable salt level over time, the water would have to be periodically drained/replaced or fresh water trucked in?

 

[chem geek]

Yup, you are correct about evaporation and fill-up having the salt level increase over time. And yes, refilling with seawater makes that rise fast in ppm terms, though would be as expected in percentage terms -- i.e. with 50% evaporation over time, the fill-up would increase salt levels by 50%; 100% of pool volume evaporated would lead to a doubling of salt level, etc.

 

[Poolsean]

most systems will shut down under high salt levels. You would need to check with the manufacturer of your system to see what is considered high, and if their system shuts down under those conditions.

 

[JamesW]

Is the seawater the only source of water available, or is there another source and they are trying to save money by using the seawater?

Depending on how much money the person has, and wants to spend, it might be worthwhile getting a reverse osmosis setup to desalinate the water if it is the only source of water.

What water source do they use for their other water needs?

No, he tells me the pool is three years old and he ha always used the seawater, this i can believe as it is starting to get deposits of salt all over the walls etc

That might not be salt. It might be calcium carbonate. Salt will not precipitate on the walls underwater, but you could get some salt deposits above the water line. Are the deposits above or below the water line? Can you post a full set of chemical results?