Acid wash or just drain and re-fill?

Oct 8, 2015
Mesa AZ
I had my water tested and 3 of the 4 "drain your pool" red flags are up there. Phosphates are sky high and just to get them down would cost a ton in chemicals. Calcium is pretty high and CYA is "normal" but fairly high in the normal range. I need to get new water in my pool as I haven't drained it yet and I've owned the house for 6 years now. My question is, do I need to acid wash it too? Or is that only when there's a ton of stains? I have a small stain or two (my brush fell in the pool over winter and I left it in there a few day too long and it caused a few rust spots) but nothing major other than some calcium on the water level tile. I'm wondering if I really need an acid wash (they're recommended often), is there another reason for them other than to remove stains? Would it remove old calcium? is that necessary? Will it hamper my pool if I don't acid wash it and just drain it all and re-fill it?

Any help is appreciated!



Mod Squad
LifeTime Supporter
TFP Expert
Jul 7, 2014
Bedford, TX

Welcome to TFP... A great place to find the answers to all your pool Myth questions... :shark:

Sounds to me like you are being Pool $tored... Phosphates being high is just a way for the pool store to take your money.. They make zero difference in pool maintenance.

If you have been a member since 2015, as your join date shows, you know we rely on test data to make decisions.. Terms like high, low, and ok are meaningless to us... we need to know the real numbers so that we can make intelligent decisions on what needs to happen to your pool.

So, it might make perfect sense to drain your pool because your CH is too high, but again... what is high??? 500, 1000 or 2000 ppm??

Is your join date really 2015??

Thanks for posting,

Jim R.


Well-known member
May 17, 2016
Phoenix, AZ
First would be to get a good test kit like the TF100 or Taylor K2006c. Pool store reading are usually wrong.

If you don't have a water softener feeding your pool in AZ CA is probably high after 6 years. But a good reading is needed.

Acid wash is pretty easy. You can always just do the spots you need and see if it makes a difference in staining. It won't take much calcium off.

Can you fill out your equipment in your signature? It can help. If you don't have a salt water generator CA isn't a big problem if you keep your pH in range.
Oct 8, 2015
Mesa AZ
Thank you both for your replies.

I have been a member since 2015 yes.

The pool store i went to actually did all the tests via the normal drop system in test kits not by putting the water into some machine that spits put a reading so i think the readings should be accurate.

Here are the numbers:
FAC 5 ppm
CH 600 ppm
CYA 80 ppm
TA 130 ppm
pH 8 (yes i know this is high and need to add some acid)
Copper 0 ppm
Iron 0 ppm
Total Dissolved Solids 3900
Phosphates 2500 ppb

Thoughts? Need to drain pool? Dont need to? I havent changed the pool water in the 6 years I've had the house.

And what about the original acid wash vs just drain?

Btw in regards to my equipment its so old that i cant read the models. I have a DE filter 48 cu. Ft i believe (has 24" grids) and a single speed pump. I use a pool robot (Pentair Prowler 830).


Mod Squad
May 3, 2014
Laughlin, NV
Do you currently work in the pool industry?
As you know being a member for over 2 years, we do not rely on Pool store tests.

Once you get your test kit, let us know your results.

IF, and I mean IF, their test for CH is correct, you are not bad at all. Typically run it up to 1000-1200 ppm prior to draining.

To do that you manage CSI by using PoolMath to calculate it. You adjust CSI by your pH and TA. Yours is very positive so in a scaling tendency. Get your pH and TA down and your CSI will be out of the scaling tendency range.
Oct 8, 2015
Mesa AZ
Im actually going to order a test kit tomorrow. Which of the two do you reccomend?

Btw, are you from Laughlin? I saw in another thread that you mentioned Nevada across from Bullhead City and I lived in Laughlin for a year then in Golden Valley when i was younger.

So if we assumed those tests were correct you'd reccomend not draining it at all? Despite CYA being 80 in a non-SWCG pool? Or dissolved solids being 3900 ppm? Alkalinity is 130 but the TFP guide says 120 is in the range and sometimes higher.


Mod Squad
May 3, 2014
Laughlin, NV
Do you currently work in the pool industry?
I recommend the TF100 with a Speedstir. The Speedstir makes doing our high CH tests much easier.

I do live in Laughlin.

Unless you have algae you can manage the CYA at 80. As long as you do not chlorinate with solid chlorine, it will fall over the next few months to 50 or so. That is about as low as you want to go here in the desert. The TDS is meaningless. The TA is way too high, I keep mine at about 60 - 70 so that my pH can be around 7.5 or so with a high CH to keep my CSI near zero to just negative for my SWCG.

The TA ranges are just that, a range. In our areas, a lower TA is needed to manage our high CH. Thus we use more acid than other areas.

If you would like to drain and deal with any calcium buildup, now is the time. Then, with proper management of your water chemistry, you will not have the calcium scale issues anymore and will only drain once your CH gets to 1000 ppm or above.
Oct 8, 2015
Mesa AZ
Laughlin is one hot place! I think it's even hotter than Phoenix. At least the Colorado river water is icy cold!

My desire to drain was more to make balancing the pool easier for me this summer and since i havent done it yet over 6 years and have read that you should empty it every 3-4 years (cleaning the calcium spots along the tile line was just anadded bonus) .

Would you reccomend draining it or is it not necessary with the numbers i have?

And also, so acid washing isnt necessary unless there's stains i want to remove?


TFP Guide
Gold Supporter
Nov 13, 2017
Central California
I'll never acid wash my pool again! This is what I know and/or think I know about acid washing. You should research it very carefully and then decide for yourself (as you are doing). It is not a trivial thing and, if warranted, should only be done with the utmost caution, by someone experienced. Acid washing works by removing a layer of your plaster, and thus the stains with it. It is not a magic liquid that removes only the stains and algae while leaving the plaster alone. Nope, it takes the plaster with it. Acid washing will reduce the life of your plaster, because it's removing a layer of it. Some estimate 1 to 3 years of life per acid wash, poof. There is a school of thought that you NEVER acid wash a pool. You live with the stains and save the money and replace the plaster when you can't go any longer. And another school of thought that you ONLY acid wash a pool as a very last resort, when the plaster is already on its last legs and the look of the plaster is so bad that an acid wash will make a slight improvement and get you an extra period of time before you have to replace the plaster anyway. The third school of thought is the most common (unfortunately, IMHO) shared by most pool maintenance companies who love to "recommend" an acid wash because it's easy to do, gets some results and doesn't take very long, so it's a high-profit item for them. They don't care (and won't tell you) that the wash will cost you in plaster longevity.

Further... acid washing doesn't really remove calcium. It'll take some with the plaster, that's about it. Calcium is harder than plaster, and if you put enough acid on the surface to dissolve the calcium, you're going to take way more plaster with it. One plaster guy I talked to claimed they use a very diluted amount of acid to "soften" the pool, and then hand sand the calcium off. I think there's a ring of truth in that. If I had stains that I just couldn't live with, and was going to empty the pool, I'd hand-sand the stains. I'd be tempted to try a very diluted mixture of acid, to get things going, but I'd be prepared to neutralize the acid immediately to stop the reaction. And I'd do so knowing that that patch will not end up feeling as smooth as the rest of the pool (nor last as long). But again, only as a last resort. I'd spot sand only, if possible, and that's it. Or use bleach. Or live with the stain.

Calcium around the water line can be blasted off, and you don't need to empty your pool for that. The blasting material falls to the pool floor and its vacuumed up.

My pool company recommended an acid wash, charged me $900 for it, and completely destroyed my plaster. I'm in the throws of legal action about it. You can read more about it here if you care to. This is a small pic of the least they did, the damage at the bottom was way worse. I had to replace all my plaster.


Acid washing is done all the time. People do get results. My pool was an exception, for sure. But based on my experience and my pool, I think it's fair to say: an acid wash performed perfectly will give you some cosmetic improvement, reduce the life of your plaster, and leave your plaster feeling kind of, for lack of a better term, "etchy." Not rough like sand paper, but not new-plaster smooth. An acid wash performed less than perfect will take additional years off your plaster's life and could possibly destroy it all together (worse case scenario).

Acid washing an entire pool, as a maintenance procedure, that exhibits only small stains, is completely inappropriate.

It is my opinion that you shouldn't acid wash your pool (especially considering how nice it looks in your picture).


Oops, just reread your question. If you're just talking about rust spots, there are chemicals you can apply that will attack the rust only and leave the plaster alone. Waaaay better than what acid would do. Something like this:

But try it on a small inconspicuous area first, to make sure it doesn't cause some other problem (something I wish my pool guys had done).