Water treatment

[chem geek]

Is a pH of 6.8 the lowest possible reading in your pH test? If so, then your pH could well be below 6.8. Do you have a "base demand" test in your test kit? If so, then that can be used to figure out how much more pH Up or equivalent you will need. If you don't have a base demand test, then you could add more pH Up, but it will increase your Total Alkalinity (TA). The 7 kgs in 78,000 gallons would raise the TA by 85 ppm so the cloudiness could be from the TA getting higher. It will probably dissipate and clear up since your pH is still low.

I would stop adding the pH Up for now. Are you certain that your pH test is valid -- is it a drop-based test or is it a test strip? You may be better off at this point just aerating your pool water to get the pH higher. Unfortunately, that requires uncovering the pool and it sounds like you need to keep it covered to keep embers and dust out of the pool. If there is a time of day or night when you can have it uncovered and not get too messy, then that will help. While it is uncovered, have the pump running and turn up your returns, assuming your returns have eyeballs where you can redirect the flow more upwards to create waves.

By the way, for the chlorine reading we call it Free Chlorine (FC) and not "CH" since that stands for Calcium Hardness (CH).

How did your pH get so low? Were you using Dichlor and Trichlor regularly and not testing for the pH?

Richard

 

[mikethaisun]

Hello Richard
Thanks for your prompt reply, I am most impressed with assistance given by TFP members.
6.8 is the lowest is the lowest reading and is checked by the drop test. I am waiting delilvery of a Duraleigh test kit.
At this time of year it can get pretty messy 24/7 so I only uncover the pool when I want to swim.
My returns are at the bottom of the pool and do not have eyeballs!! what are they anyway?

I don't get waves, I get bubbles when the pump is on filter or replenish.

The problem has probably been caused by the pool being covered for about 6 weeks (our winter) without any testing. When I took the cover off there was green stuff on the walls and the water was a pale green also. I used Sodium Hypochlorate to get rid of the algea and then checked for pH, it loks like I didn't have any from what you say. I was using Trichclor for adding Chlorine.

I hope this is usefull to you and thanks again for your interest.
Regards
Mike

 

[chem geek]

Remember that "returns" are where the water returns (comes back into) your pool. These are not the floor drains or skimmers where water leaves your pool to go to the pump. Are you sure that the returns are at the bottom of your pool? Normally they are a foot or so below the surface of the water and are placed on several walls around the pool to create a circular water flow.

It's not that you have no pH, but rather that it is too low. pH isn't something normally described as being something you are missing, but as a measurement scale where you can be too low or too high. It can be thought of like temperature where you usually would not say you don't have any temperature, but rather that it was too low or too high relative to your target.

This link shows an eyeball fitting. Basically, the returns are just pipe ends going into the pool so are holes where water comes out. Eyeballs are a fitting over that pipe that allow you to direct the water flow in a particular direction and they are called eyeballs because they look like eyeballs since they are spheres with a hole bored through them so looking at them looks sort of like an eye with a circular hole, sort of like an iris or pupil.

I'm not quite sure what you can do at this point. I don't think it's a good idea to add more pH Up since your cloudiness may indicate that the TA is already too high. To get the pH higher, you could use 20 Mule Team Borax if you could find it or you could aerate the water if you could keep your cover off for a while. I suspect that your pH is probably getting close and only a little under 6.8 at this point, but I can't be sure.

Richard

 

[mikethaisun]

Hello Richard
I definitely do not have 'eyeballs' there are three circular openings in the bottom of the pool, one near each end and one in the middle. I was told that water is recycled through these to the filter and then returned to the pool. Water is also added to the pool through these openings to when there is a neeed to raise the water level in the pool. There 4 valves in the pump house and they are set for different uses, Filtering, topping up and back washing.

I have checked the FC and pH this morning and both levels seem to be OK, the FC is about 3 and the pH is nearly 7.2. I have taken the cover off and the water is starting to clear.

I think I will wait for the super duper test kit to arrive before adding any more Chlorine or Soda Ash.
Thanks for your help
regards
Mike

 

[mikethaisun]

Hello again Richard
24 hours on, results still thw same as previous days. Water is still cloudy albeit has cleared a little. There is a whiteish sheen on top of the water that disipates if you disturb it but returns when the water is still.

I have left the pool cover off, will the sun eventually clear this off? I hope I do not need any more chemicals as they are hard to find in this part of the world.
Regards
Mike

 

[chem geek]

If the cloudiness is dead algae, then keeping your Free Chlorine (FC) at shock level relative to the Cyanuric Acid (CYA) level is important. Continuous filtration and periodic cleaning/backwashing of the filter. Unfortunately, you didn't test all of your water chemistry levels so we don't know the CYA or the Calcium Hardness (CH) nor even know what kind of filter you have, do we? The Pool School article Defeating Algae is relevant here, but without good numbers you are shooting in the dark. Just note that it does take up to a week to clear the pool of algae unless you spend more money with a clarifier or floculant, but that's not necessary unless your circulation is really poor.

Assuming you have some CYA in your pool, I suggest raising your FC to around 10 ppm and keeping it there until the pool clears.

I do find it very surprising that your returns (where water comes in from your pump) are in the floor of the pool. I guess that's how they build them where you live.

Richard

 

[SMWill42]

Hello,

Could you at least send us a picture of your pool and pump so we can get some idea of what the set up is?

Thanks,
Susan

 

[mikethaisun]

Hello Richard and Susa
Thank you for your continued support in tyring to help me the the water cleanliness problem.
The present problem occurred when I added Soda Ash as the drop test readings were only showing 6.8, FC levels were good and the water was clear. I added an additional 2kgs of Soda Ash and the present problem soon maifested itself. The surface of the water has a oily looking sheen to it that breaks up when disturbed but returns when the water is still.
I am filtering the pool regularly through a sand filter.
How do I raise the FC level to 10? my test kit only goes to 3.
I have not yet received the Duraleigh test kit and would like to post photo's for you but do not know how to do that, sorry for being a wassock!
Regards to all
Mike

 

[mikethaisun]

Hello Again Richard
24 hour on. I have added the required amount of chlorine as suggested, I did this by using the 'Pool Calculator' entering the current test result of 3 and the desired level 10 which suggested I needed to add approx 600gms of Trichlor. I did this and then checked for pH and FC an hour later both were fine it seems. the colour in the FC was much darker than the 3 level and the pH colour was spot on 7.2.

I hoovered the pool bottom before doing this and backwashed out a lot of dust that had settled in the pool due to leaving the cover off. I still have the same problem with the oily looking sheen
on top of the water but can see the bottom of the pool at the shallow end, the deeper the water the murkier it looks.

Should I leave it covered for a few days and see if that makes a difference or add more chlorine/Sodium Hypochlorate? or what else should I try. I am going to the city in the next few days and maybe be able to get other chemicals when there.

Regards
Mike

 

[JasonLion]

Getting a better test kit would really help. Without complete water test results it is very difficult to guess at what might be happening.

 

[mikethaisun]

Hello Jason
The test kit has arrived and below are the results of the first test.
FC 1.5
CC 0
TC 1.5
pH 7.2
TA 290
CH 250
CYA 100

With the CH test the colour turned to violet, is that considered blue, or, I may be colour blind!

Do these results give you a better indication of what is required to get the water clear. One thing I need to do is get the FC level up, what do you suggest I aim for.
Regards
Mike

 

[JasonLion]

Alright, that helps a lot.

Your CYA level is too high. Very high CYA levels require far higher chlorine levels and create other secondary problems. You should replace water to get your CYA level down to the 30 to 50 range. One thing to keep in mind is that CYA levels above 100 will often read on the test as if they were 100. So your CYA level might actually be much higher.

The most appropriate FC level depends on your CYA level, see this chart. At very high CYA levels you need extreme amounts of chlorine to fight algae. It is almost always simpler to lower the CYA level first, and then fight the algae.

Longer term, your TA level is rather high. I don't think your current problems have anything to do with this, but longer term it would be best to work on lowering your TA level.

 

[PaulR]

One thing to keep in mind is that CYA levels above 100 will often read on the test as if they were 100. So your CYA level might actually be much higher.

The thing to do is dilute your pool water sample half-and-half with tap water, then test the diluted sample. Double the reading, of course.

Longer term, your TA level is rather high. I don't think your current problems have anything to do with this, but longer term it would be best to work on lowering your TA level.

If you do a partial drain/refill to lower CYA, then this might also lower TA, depending on the TA of your fill water. (Worked for me, in a similar situation.)
--paulr

 

[mikethaisun]

Thank you Jason and Richard
I will try what you advise. I have to travel a long distance to get 90% Chlorine but can get 70% fairly close to home. Is it OK to use 70%?
Regards
Mike

 

[JasonLion]

The percentage of chlorine doesn't really matter unless you are calculating what it costs. What matters is which form of chlorine it is. The five common forms of chlorine are bleach/liquid chlorine, trichlor, dichlor, cal-hypo, and lithium-hypo. Trichlor and dichlor add CYA and lower the PH. Cal-hypo adds calcium. Lithium-hypo tends to be expensive. And bleach requires more carrying (the water adds weight). You should know what kind of chlorine you are getting and if the additional things it does are acceptable.

For example, cal-hypo adds calcium. Give your current calcium number, that will be alright for a little while. But eventually you calcium level will get too high.

 

[mikethaisun]

Thanks Jason
Sodium Hypochlorate seems to be the cheapest form of Chlorine, will this do the job or should I stick with ordinary bleach or trichclor.
I have a pump rigged to draw water from the pool and return it causing waves I hope this will provide the aeration you mentioned before. I don't where I could get Muriatic acid even if I knew what it is.
Regards
Mike

 

[SMWill42]

Bleach (liquid chlorine) would be best. Muratic acid is used to clean hard surfaces such as brick and concrete. It can be found at a hardware store where you get building materials.

Susan

 

[JasonLion]

Bleach is the same thing as sodium hypochlorite, also sometimes called liquid chlorine or liquid shock. They come in different concentrations, bleach is often around 6% and sodium hypochlorite is often 10% or 12.5%, but they are chemically identical. The higher concentrations mean less carrying, which is nice. Sometimes one form is cheaper, sometimes the other form is cheaper, other than that they are the same.

In any case, bleach/sodium hypochlorite is a great choice.

Muriatic acid is sold by most of the big box hardware store (Lowes, Home Depot) in addition to several other places. It is a concentrated liquid acid that is almost always the least expensive way to buy acid. It fumes a little when you open the container. You really want to avoid breathing the fumes. It is also a good idea to wear eye protection when handling it.

 

[frankthailand]

hello Mike
muratic acid is hydroclhoric acid available here in 20 litre containers for 450bt. (can store for a long time)

liquid chlorine 10% also comes in 20 litre containers for 250 bt (must be stored in dark cool place away from the acid!!!) maybe six months it loses strength over time.
these are the prices in Phuket. (poo-ket, phonetically speaking )

with a cya level of 50 i estimate 1 to 2 litres daily, depends on how many people use the pool. ( example big party double it)

for areation you want the the water to be splashing

where do you live
Happy swims Frank

 

[mikethaisun]

Hello Frank, Jason and Susan
Thanks for the information, I live in the very rural North East, its very quiet but hard to get anything other than the basics for survival unless I go to Korat or Bangkok. What sort of store sells the acid.

I am still aerating the pool and will test this afternoon to see if there are any significant changes.
Thanks again
Mike