Acid wash or re-surface

[JamesW]

If you do not drain, then the iron stays in the water and it eventually comes back out as a stain.

Ascorbic acid only "unoxidizes" the iron, but the iron stays in the water.

Iron "rusts" and oxygen and chlorine in the water will cause it to rust or oxidize again.

It might stay nice for a day, week, month or year depending on the circumstances.

There's no telling how long it will stay nice and when the stains will come back.

If your water supply has high iron levels, then you have to remove the iron before filling with some sort of filter.

Maybe try a treatment without draining to see how well it goes and how long it lasts.

If necessary, you can always do it again and drain if necessary.

Most pools that float seem to be in Florida, so be very careful to verify that draining will not cause damage to the pool.

Note that different metals have different reactions to different treatment chemicals and some reactions can be bad and make the stains worse.

You might have copper, silver, manganese etc. in addition to iron.

So, each metal might react differently and it might turn out well or it might do nothing or it might make the stains worse.

 

[william13]

If you do not drain, then the iron stays in the water and it eventually comes back out as a stain.

Ascorbic acid only "unoxidizes" the iron, but the iron stays in the water.

Iron "rusts" and oxygen and chlorine in the water will cause it to rust or oxidize again.

It might stay nice for a day, week, month or year depending on the circumstances.

There's no telling how long it will stay nice and when the stains will come back.

If your water supply has high iron levels, then you have to remove the iron before filling with some sort of filter.

Maybe try a treatment without draining to see how well it goes and how long it lasts.

If necessary, you can always do it again and drain if necessary.

Most pools that float seem to be in Florida, so be very careful to verify that draining will not cause damage to the pool.

Note that different metals have different reactions to different treatment chemicals and some reactions can be bad and make the stains worse.

You might have copper, silver, manganese etc. in addition to iron.

So, each metal might react differently and it might turn out well or it might do nothing or it might make the stains worse.

I get the part that there may be more than one metal. I thought the role of sequesterent was to capture the iron in solution. Did I misunderstand? BTW I dont want to float my pool....that sounds horrible!

 

[JamesW]

I thought the role of sequestrant was to capture the iron in solution.

It does, but sequestrant breaks down and you have to keep adding it forever.

Sequestrant breaks down into phosphates, which can become problematic if the phosphate levels get too high.

Also, it is not perfect, the iron can still be oxidized and create a stain, but it happens more slowly.

 

[JamesW]

BTW I don't want to float my pool....that sounds horrible!

Are you near water like a lake, river, stream or ocean?

If yes, what is the pool bottom elevation compared to the water surface elevation?

The volume of water displaced determines the total lifting force of the water.

If the displacement is high, the force is also high and the pool can float.

For example, if the displacement is 1,200 gallons, then the lift is about 10,000 pounds.

 

[Newdude]

You may also have a high water table independent of nearby bodies of water.

Or flash floods could happen while the pool is empty.

Basically you are concerned with any scenario which may turn the pool into a boat instead.

 

[william13]

Sure! I get that totally. I am in between ocean and intercostal essentially on an island in south florida. Yes everyone worries about pool popping down hair. I would imagine if I drained pool I would leave some in but if I can inquire again about the role of sequesterents grabbing the iron in solution. Do they settle on bottle and allow vacuuming or something?

 

[JamesW]

Sequestrants are molecules that iron ions attach to.

They mostly float around in the water.

1-Hydroxyethylidene-1,1-diphosphonic acid; HEDP

Etidronic acid - Wikipedia

en.wikipedia.org

pKa: pK1 1.35 ±0.08; pK2 2.87 ±0.01; pK3 7.03 ±0.01; pK4 11.3

 

[JamesW]

Sulfamic acid is also a type of chelant or sequestrant that forms a relatively stable molecule with metals like copper.

Chelant is a chemical compound that forms stable, water soluble complexes on reaction with metal ions.

A chelant prevents metal ions, such as calcium, magnesium, iron, and manganese, from forming insoluble precipitates with other ions in a solution by binding to the positively charged metal ions.

Sulfamic acid forms a compound called Copper(II) Sulfamate, which is a relatively stable compound.

Molecular Formula: CuH₄N₂O₆S₂.

Molecular Formula: Cu(NH₂SO₃)₂.

CuO + 2NH₂SO₃^- + H₂O --> Cu(NH₂SO₃)₂ + 2OH^-

Copper Oxide + sulfamate ion + water --> Copper sulfamate + hydroxide.

CuO + 2NH₂SO₃H --> Cu(NH₂SO₃)₂ + H₂O

Copper Oxide + sulfamic acid --> Copper sulfamate + water.

Note: Sulfamic Acid is a strong acid (pKa =1.0) and completely dissociates in an aqueous solution.



View attachment 549511

The sulfamic acid also forms chlorosulfamate and dichlorosulfamate, which locks the chlorine up for months, which is one of the reasons that you need to drain and refill after the stains are lifted.

You also need to get rid of the metals that are attached to the sulfamate ions because they will eventually form new stains.

Note: Never drain unless you verify that it is safe to do so.


View attachment 549497


View attachment 549498

View attachment 549499View attachment 549509

 

[JamesW]

EDTA is also a sequestrant used to hold iron and other metals.

The bond is not perfect or permanent and the sequestrant eventually breaks down and it releases the metals back into solution.

Ferric EDTA - Wikipedia

en.wikipedia.org

 

[william13]

I am sure you made this point but if I do ascorbic acid and then sequestrant do I have to change water or does the latter form a complex that sinks and needs to be vacuumed. If I need to drain pool I think I need to have professionals on site!

 

[JamesW]

I am sure you made this point but if I do ascorbic acid and then sequestrant do I have to change water or does the latter form a complex that sinks and needs to be vacuumed.

It forms a complex that remains in the water; it does not precipitate out.

 

[Bperry]

I am sure you made this point but if I do ascorbic acid and then sequestrant do I have to change water or does the latter form a complex that sinks and needs to be vacuumed. If I need to drain pool I think I need to have professionals on site!

You can pick replacing the water after ascorbic acid treatment or adding sequestrant forever.

 

[mknauss]

A no drain exchange is not difficult and safe for your pool.
See Draining - Further Reading

 

[william13]

It forms a complex that remains in the water; it does not precipitate out.

ty

 

[william13]

A no drain exchange is not difficult and safe for your pool.
See Draining - Further Reading

will read tonight ty

 

[kimkats]

Is my maintenance person trying to dupe me?

He is trying to get in your wallet!

 

[william13]

Hi folks I've been away a few days and I am back to figure out what direction I will go in.
I have decided that the "No Drain Exchange" is a good idea but beyond my capabilities.
I have spoken to a few pool maintenance companies and cleaning companies and to my absolute suprise that will not do the ascorbic acid thing. So this is what I think I should do.

1. I would like to do the AA protocol and of course add the sequestrant.
2. I now realize that the sequestrants effects are temporary and unless water chronically treated with them they break down and minerals are released and will re-deposit

So I think I should do the AA, add the anti algae, add the Sequestrant and then hire someone to drain by pool as I do not have the experience to know if I am doing everying to keep it from popping. I do understand their might be valves on botton of pool that allow water equalization and minimize chance of hydrostatic pressure induced popping and would like to know more about this.

 

[Bperry]

Hi folks I've been away a few days and I am back to figure out what direction I will go in.
I have decided that the "No Drain Exchange" is a good idea but beyond my capabilities.
I have spoken to a few pool maintenance companies and cleaning companies and to my absolute suprise that will not do the ascorbic acid thing. So this is what I think I should do.

1. I would like to do the AA protocol and of course add the sequestrant.
2. I now realize that the sequestrants effects are temporary and unless water chronically treated with them they break down and minerals are released and will re-deposit

So I think I should do the AA, add the anti algae, add the Sequestrant and then hire someone to drain by pool as I do not have the experience to know if I am doing everying to keep it from popping. I do understand their might be valves on botton of pool that allow water equalization and minimize chance of hydrostatic pressure induced popping and would like to know more about this.

The hydrostatic valve in the main drain is just for long term draining. If you’re filling it right back up there’s no valves needed to be messed with. You can’t get to those valve until all the water is drained out anyway so you need to ensure the pool doesn’t pop out long before you decide to drain.

Is there a particular reason you found the no-drain exchange beyond your capabilities? It was designed to be the safest non-technical way to exchange water. It’s really not difficult and the only risk in the process is spending extra money exchanging water that didn’t need to be exchanged.

 

[william13]

The hydrostatic valve in the main drain is just for long term draining. If you’re filling it right back up there’s no valves needed to be messed with. You can’t get to those valve until all the water is drained out anyway so you need to ensure the pool doesn’t pop out long before you decide to drain.

Is there a particular reason you found the no-drain exchange beyond your capabilities? It was designed to be the safest non-technical way to exchange water. It’s really not difficult and the only risk in the process is spending extra money exchanging water that didn’t need to be exchanged.

It has a lot of steps and to a newbee it seems that any one error could sabatage the whole process

"In general, it is safer to exchange water in a pool rather than drain. We’d like to share a method done from time to time by members of TFP.[3] The process to exchange water depends on determining a few factors:

• The temperature of your fill water versus the pool water temperature.
• Does the pool water have salt in it above 2000 ppm or a Calcium Hardness of 800 ppm or more?
• Essentially, is the pool water high in Total Dissolved Solids (TDS).

Where will the effluent be discharged?​

Prior to exchanging the pool water to fresh, you need to determine where is the effluent (pool water you remove) going? Some municipalities have requirements. Be sure to research that. In most areas, it is easiest and best to drain to your sewer clean out at your home. If the water has salt in it, be wary of draining to your grass or plants. It may do them harm.

What pump to use?​

You also will need a pump to remove the water from the pool. It is not advised to use your pool pump. It is a fairly expensive piece of equipment and if by chance it loses prime during the process you could damage it. A low power (1/3-1/2 hp) submersible utility pump is a good choice.

The rate at which it pumps is very dependent on what hose size and length you use to direct the effluent. If using a garden hose to a sewer cleanout, expect a flow rate of 6-9 gallons per minute.

Pump from the deep end or near the surface?​

To determine whether you pump from the deep end of the pool or from near the surface of the pool, depends on your fill and pool water characteristic.

Adding water to the deep end while pumping from a top step or near the surface is recommended if your fill water is much colder (>20F) then the pool water.

Put the pump in the deep end and fill from the shallow end if your fill water is nearly the same temperature as the pool water, you have a saltwater pool, or have very high CH. Put the fill hose in the skimmer, if you have one, in the shallow end. If no skimmer, then use a bucket to put the water hose in and have the top of the bucket above the pool water surface. Be sure to secure the hose to the bucket.

Replacing water in-place process depends on several factors:[4]

• Pool Water TDS (PWTDS)
• Pool Water Temperature (PWT)
• Fill Water TDS (FWTDS)
• Fill Water Temperature (FWT)

DeltaT = (PWT - PWTDS / 165) - (FWT - FWTDS / 165)

If DeltaT is positive, then you want to fill at the lowest point and extract at the surface and at the greatest distance from the lowest point.

If DeltaT is negative, then you want to extract at the lowest point and fill at the surface and at the greatest distance from the lowest point. <-Preferred as it is easier to do with a drain pump and you can fill inside one of the skimmers.

If |DeltaT| < 5, then there will be a lot of mixing.

Salt is the largest component of TDS. No matter what chlorination method you use, salt is added to the pool water and can be significant after many years. Every 1000 ppm of salt is worth about 6F in temperature difference.

Balance the water flow out and in​

Be sure to balance the water out and water in so the pool level stays the same.

When you have the pump you will use, take the effluent hose and fill a 5 gallon bucket while timing it. Calculate your gallons per minute (gpm) from that. Then you can estimate how long to run the process.

It is suggested to exchange 5-10% more water than needed to reduce your CYA/CH/etc to account for errors.

Be sure your pool pump is disabled during this process.

Once started do not stop until complete​

Once started do not stop until you have exchanged the amount of water you wish."

 

[kimkats]

We can and will walk you through it. The worst that could happen is the two waters mixing. That is NO big deal. It will mean a bit more exchanging of water but that is all.