Baking soda won't disolve

[xoomer]

I added about 5 lbs of baking soda to my 14k gallon, salt water, pool about 3 weeks ago and it made the water very milky. I found out afterwards that the baking soda had expired some time ago so that may have caused the problem. In any case, I'm having a heck of a problem trying to clear the water.

First I tried regular clarifier, over and over, but it didn't help much. I also tried my manual vacuum but the baking soda just came back passing through the filter and going into the pool. Lately I've been vacuuming with a battery operated vac, stuffing it with 7 fine mesh nets. This has helped quite a bit but some of the baking soda is so small that it goes through the vac, back into the pool. I've also tried "Clear and Perfect" which helped a bit, but hasn't worked as well as I had hoped.

I've managed to capture a lot of the baking soda but the water is still milkey after all these treatements so I'm wondering if someone has had this same problem and can suggest something that will clear the water once and for all...

TIA

 

[dmanb2b]

Welcome to TFP!

The only thing that will fix this is fixing your filter as it should not be bypassing visible debris. Secondly, post up a full set of test results as it could be a chemistry issue as well.

 

[xoomer]

Thanks for the welcome and the reply. Below are the latest test results done 4 days ago:

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Also, these are the filters I am using--both are fairly new:

• Pleatco Pure, PCM100SV--30"x7" cartridge filter
  Unicel C-7625--10"x7" cartridge filter

Thanks again...

 

[duraleigh]

xoomer,

Welcome to the forum. :lol: I will be surprised if baking soda is the culprit, expired or not, baking soda is pretty inert and I don't recall one instance of it clouding a pool other than very temporarily.

Stop using clarifier. It is obviously not working. Can you post a pic of your water clarity. Your problem is a bit puzzling but a pic my elimnate some of the possibilities. In any event, we can help[ you get it clear.

Can you actually see cloudy water returning to the pool or is the pool simply staying cloudy even though you are running the filter.

 

[xoomer]

I will try to get a picture tomorrow before I run the pump, and after I vacuum since that is when it gets cloudy. If the water settles down overnight it is fairly clear in the morning but once I run the vacuum it becomes cloudy. At first I had a lot of white residue in the pool--it was as if I had taken a bucket of white sand and poured it along the edge of the pool. There would be areas of buildup of white streaks in the deep end and on the sides. However, once I started the vacuum the white powder would enter the pool from the return inlets making the water cloudy--I could definitely see the residue coming from the inlets.

I don't know what else it could be since the water was fine before I put the baking soda in and immediately caused a problem by not dissolving. I don't remember the exact expiration date of the baking soda but I believe it was at least 5 years old. I just bought this house and pool about 7 months ago and the baking soda was left over from the previous owner with some other pool chemicals.

Thanks for the help...

 

[chem geek]

Lower your pH by adding acid. If the water clears up then it's calcium carbonate clouding. Even though at 85ºF with your pool store's numbers for your pool water the saturation index would be -0.14, I suspect those numbers may be in error and one or more of pH, TA and CH may be higher than shown. You should really get your own good test kit, either the TFTestkits TF-100 or the Taylor K-2006. You won't regret it and you'll be able to take charge of your pool.

 

[xoomer]

Here are a couple of photos I took this morning--this one is before and after vacuuming:

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This is some of the residue I vacuumed up:

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I actually do have a Taylor kit so I took the following readings:

FC 2.5
TC 2.0
CH 340
TA 80
Ph 7.7
salt 2920

Thanks...

 

[duraleigh]

1. That may be, in fact, baking soda that hasn't dissolved. It's purely a guess and it will be the first time it has been reported. I suppose it may have changed enough chemically over the time it's been on the shelf. Lesson learned, huh? :-D

2. Unless you just recently lowered your pH. your numbers do not indicate calcium precipitation.

3. Vacuum very slowly. It's tedious but you will stir up less and capture more.

4. No need for clarifier, you can remove all that mechanically with the vacuum.

a. Your FC is a bit low.....If your CYA is really 40, 3-5ppm would be better. (FC and TC numbers you report appear reversed)

In short, you can clear your pool by vacuuming slowly and being patient.....it may take a few more attempts.

 

[xoomer]

It does appear to be baking soda but I don't know how to tell for sure. I've been vacuuming every day for a few weeks and it is a lot less cloudy now--at first I couldn't even see the main drain or the bottom of the ladders.

Well, thanks for the help, I'll just proceed on vacuuming and will remember to check the expiration date on everything in the future...

 

[chem geek]

What happens if you add a little acid (even vinegar) to the white powder you've collected? Does it fizz? If it does, then it's some form of carbonate, but other than calcium carbonate it doesn't make sense to be baking soda since that would still dissolve readily in water. It's got to be some sort of precipitate. Even if baking soda were to decompose (usually from hot temperatures), it would still be to soluble compounds with the sodium bicarbonate becoming sodium carbonate becoming sodium oxide (which violently becomes sodium hydroxide in water). I'm still betting on it being calcium carbonate that was formed because the baking soda was added too quickly and your pool was already near saturation. This is similar to the calcium cloudiness that occurs when one adds either pH Up or calcium chloride to a pool that is near saturation, but usually such cloudiness eventually dissipates.

Is this substance you collected hard or is it powdery?

 

[JamesW]

I would suspect paint chalking if the pool is painted. Try rubbing your hand on the wall to see if it leaves a white residue on your hand.

If the container of baking soda was not factory sealed, then there might have been some other product in the container.

Another possibility is that the plaster is in an advanced state of deterioration from prior poor chemistry.

 

[xoomer]

What happens if you add a little acid (even vinegar) to the white powder you've collected? Does it fizz? If it does, then it's some form of carbonate, but other than calcium carbonate it doesn't make sense to be baking soda since that would still dissolve readily in water. It's got to be some sort of precipitate. Even if baking soda were to decompose (usually from hot temperatures), it would still be to soluble compounds with the sodium bicarbonate becoming sodium carbonate becoming sodium oxide (which violently becomes sodium hydroxide in water). I'm still betting on it being calcium carbonate that was formed because the baking soda was added too quickly and your pool was already near saturation. This is similar to the calcium cloudiness that occurs when one adds either pH Up or calcium chloride to a pool that is near saturation, but usually such cloudiness eventually dissipates.

Is this substance you collected hard or is it powdery?

I put some vinegar on the residue I collected today but nothing happened--of course this stuff has been in the water for several weeks so it is pretty water logged.

The baking soda was added fast, I believe I just poured in the entire 5 lbs all at once.

The residue I get when vacuuming is mainly powdery.

These are the test results a couple of days before I put in the baking soda:

Thanks...

 

[xoomer]

I would suspect paint chalking if the pool is painted. Try rubbing your hand on the wall to see if it leaves a white residue on your hand.

If the container of baking soda was not factory sealed, then there might have been some other product in the container.

Another possibility is that the plaster is in an advanced state of deterioration from prior poor chemistry.

There is no white residue when rubbing the wall.

The baking soda was left over from the previous owner in the baking soda package but it had been opened, and re-sealed--like a zip-lock. It had the appearance of baking soda, but who knows if something else had found its way into the package.

I don't think it is the plaster since the pool water had been clear for several months after I bought the house and only became milky once I put the baking soda in the pool.

Thanks...

 

[Melt In The Sun]

If it doesn't fizz, it's not baking soda. Something else is going on!

 

[UnderWaterVanya]

Any dry baking soda left to test with?

Try some dry and then wet some and repeat the test. If it is baking soda either way will make it react as far as I know. I know that drinking a baking soda solution and then lemonaid or other acid drink will cause serious belching...

 

[xoomer]

If it doesn't fizz, it's not baking soda. Something else is going on!

It was about 5 years beyond the expiration date when I put it in the pool and it has been in the water over a month--couldn't those two things cause it to become degraded enough not to fizz?

I tried to call Arm & Hammer's technical department but was cut off by the first person who answered the phone saying there is no such department and she was the only one I could talk to. Of course she only had guesses when I started asking questions.

Thanks,

 

[xoomer]

Any dry baking soda left to test with?

Try some dry and then wet some and repeat the test. If it is baking soda either way will make it react as far as I know. I know that drinking a baking soda solution and then lemonaid or other acid drink will cause serious belching...

Unfortunately, the package got tossed in the garbage a while back.

I let some of the residue dry out for a while this morning but it is only a small amount of powder and it didn't want to fizz.

Thanks,

 

[chem geek]

The expiration for the baking soda is because it will slowly turn from sodium bicarbonate into sodium carbonate which is a component of baking powder (and is in pH Up) and sodium hydroxide which is lye. Basically, carbon dioxide gets liberated from the baking soda:

2NaHCO₃ ---> Na₂CO₃ + CO₂(g) + NaOH
Sodium Bicarbonate ---> Sodium Carbonate + Carbon Dioxide + Sodium Hydroxide

The above result (sodium carbonate and sodium hydroxide) won't bubble if only some acid is added, but will if enough is added (also if a stronger acid like Muriatic Acid is added since it takes less). However, these are still soluble in water though with a lot added would form calcium carbonate. So while that could explain cloudiness, it doesn't explain why what you are now seeing as residue from the pool doesn't bubble with acid.

 

[xoomer]

The expiration for the baking soda is because it will slowly turn from sodium bicarbonate into sodium carbonate which is a component of baking powder (and is in pH Up) and sodium hydroxide which is lye. Basically, carbon dioxide gets liberated from the baking soda:

2NaHCO₃ ---> Na₂CO₃ + CO₂(g) + NaOH
Sodium Bicarbonate ---> Sodium Carbonate + Carbon Dioxide + Sodium Hydroxide

The above result (sodium carbonate and sodium hydroxide) won't bubble if only some acid is added, but will if enough is added (also if a stronger acid like Muriatic Acid is added since it takes less). However, these are still soluble in water though with a lot added would form calcium carbonate. So while that could explain cloudiness, it doesn't explain why what you are now seeing as residue from the pool doesn't bubble with acid.

I vacuumed up a bit of residue today, fortunately it is getting less and less, and then dropped it in some muriatic acid--and this time it did fizz! The previous time I only used vinegar and it didn't fizz at all.

So, would it be possible to put enough muriatic in the pool to dissolve the rest of the baking soda, or would that require too much acid?

Thanks...

 

[duraleigh]

Vacuum it up. There is no telling how long it will take or how low your pH will have to be.