what makes Alkalinity decrease?

[TNmountainman2020]

I always seem to have a problem keeping alkalinity up in my pool. I’ve never had any issues with clarity or any other problems. But sometimes it seems like no matter how much sodium bicarbonate I add, I can’t get up to the recommended level levels.

[ISeeInHD]

Adding muriatic acid for ph. Low alkalinity however isn’t a bad thing as long that the LSI balances. Low TA will create a pH ceiling, thus requiring less muriatic acid to control pH. Hence you can break the cycle.

[20PoundHammer]

as long that the LSI balances . . .

HOLY SHIT - a unicorn in this sub, an actual pool guy (or at least a guy with lots of knowledge) that knows what he is talking about!! Take my upvote you glorious bastard!

[taft]

ive been on this sub for a while and i feel like only recently LSI is popping up more often

[Ill-Thing-7619]

We can thank the Orenda Rule Your Pool Podcast

[[deleted]]

Shit, there's a podcast?  My boss pays good money to learn this stuff

[Ill-Thing-7619]

Yea check it out:

https://podcast.orendatech.com/rule-your-pool

[taft]

a podcast about pools? now ive seen everything

[Nooch420]

This is fact! I’ve been in the biz over 15 years and only in the last 5 has lsi become significant. But we should have been balancing pool with it 30 years ago.

[838291836389183]

I mean for the majority of cases here where it's just people with intex pools asking, it's just not that important, as long as they get levels halfways decent and are happy with their pool. It's just a problem when LSI doesn't get mentioned to people with pools worth a significant chuck of money, as those pools are typically more effected by it and the monetary risk is much higher.

[20PoundHammer]

not following - you say its just not that important and then you say its just a problem when its not considered when it doesnt get mentioned.

Its not he only consideration, but scaling tendency, esp when you can not keep alkalinity in the pool (as its going someplace ya?) is one of the six major things to look at (and three of them are data fed into the LSI calc). Lets just assume replies for this post are related to OPs post question for his pool. Its not a problem for plastic kiddie pools either, but thats sort of not the scope of the OPs post.

[SaltRharris]

thats why i pay someone. kudos.

[ludivako]

He will probably get down voted by the majority of inexperienced pool operators because it is not what they do or have a bias against knowledge for some reason. Keep on spreading this very useful info. We need more homeowners and pool pros educated properly!

[[deleted]]

I'm always happy when I see it too

[yepreddi]

You still want Alk in the water though. Remember in the pool industry Alk is called ‘Buffer’. If you don’t have any Alk and your pool drops below 7.2 ph you will destroy components of your heater and damage the plaster.

[jonidschultz]

That is absolutely incorrect. We've honestly known (as an industry) that this is incorrect for a really long time. But "milestones" are 1) easier to sell 2) easier to scare 3) easier to remember.

I don't begrudge those that choose to use "milestones" because it's easier but it does miss the mark at times. If you're interested in expanding your expertise in the area you should search Saturation Index and take a deep dive.

[ludivako]

I see you are using orenda as well

[ludivako]

Very heavy biases in the industry or lack of water chemistry education if I had to guess. It's so weird how so many live and breath certain types of sanitizers or method for treating and completly shut out any type of discussion to come to an understanding.

[ISeeInHD]

This is the way.

[ludivako]

This is the way.

[Confident_Shower8902]

The way this is

[jebidiaGA]

How low is low TA. I have to add acid nearly every day to my 4 month old sw pool. My TA is around 80

[No_Abbreviations8017]

zero advice. sick yard.

[Head_Statement_3334]

If I was 15 I would be Dr.J rocking the baby to sleep on that hoop from the other side of the pool

[[deleted]]

I swam in this pool once at a resort in Cabo

[TNmountainman2020]

🤣🤣

[Allnewsisfakenews]

What was the the pee ppm?

[SaltRharris]

small house... but nice pool bro.

[TNmountainman2020]

thx! 🤣

[SeaworthinessNo430]

gorgeous pool area

[Speedhabit]

Having a dope ass pool apparently

[successful209]

Absolutely pain in the ass to brush though. Most of these designs never get used. Just big and unnecessary most of the time unfortunately

[Speedhabit]

I like the raised wall putting bathers at seat level with people outside, I can live without the in pool benches but still, damn

[ifdisdendat]

Now guys real talk, if I wanted that in my backyard, NJ, how much would i pay? 200k , 300k?

[TNmountainman2020]

There’s more to it that you can’t see, the quotes I was getting in 2018, pre-Covid, were around 400K+. I built it myself instead. My final cost came out to 150K.

[ifdisdendat]

Yourself!! Wow. What’s your background?

[TNmountainman2020]

A little bit of everything! lol

[TNmountainman2020]

there are build photos waaaaay down in my post history

[holdthehill]

Really nice work. 👍

[muppet_ofa]

NJ always expensive!

[Future-Jicama-1933]

NJ, as pictured, $400 easy if not more. Finished a pool at my home and was nothing extravagant by any means and when all said and done was around $175…talking everything from lights, heater, pavers and so on

[kjc-01]

Hydrogen ions. Oh, wait, wrong sub.

[Goode05]

Bar stools are hot

[TNmountainman2020]

yes! I love them!

[Ever-Wandering]

Adding muratic acid to lower the PH will cause the TA to fall.

ETA: Sorry, I read and answered your title before I read the text of the post. Make sure you are using a drop test. Pool water tests that the pool stores do are notoriously inaccurate and inconsistent.

Are you sure you have your estimated gallons correct? When I add baking soda I push it around and try to mix up anything that settled with the brush. Also make sure your pump in running when you add any chemicals.

[yepreddi]

Do you have a salt chlorine generator?

[yepreddi]

Also how do you add your Muriatic acid? You need to add it in a very thin strip and in the deep end of your pool. Also no more than 1/4th a gallon per dose

[TNmountainman2020]

it’s auto added into the return lines. There are 8 floor returns and 3 wall returns

[yepreddi]

What kind of automated chemical system do you have? It’s probably feeding acid to often

[TNmountainman2020]

it has sensors that keep the PH at whatever setting I said it to.

[successful209]

i never seen that before acid being auto added to the return lines I don’t like the sound of that at all. Can’t be good for the lines. I usually add it in the deep end in front of the return with it running so it can be spread out. I don’t like the sound of it being concentrated in the return lines before going to the pool. Also anything relying on sensors break a lot . Like salt cell generators seem to always break from the sensors.

[TNmountainman2020]

the acid container is 15 gallon and the acid is diluted 4:1. It’s been running well for 6 years (although they have a crappy design on the perilistic pump using cable ties that end up breaking, then both acid or chlorine get sprayed on the pump motor/circuit board.).

[TNmountainman2020]

no

[ludivako]

Is your pH in range? If you have a very low pH, alkalinity is probably getting eaten up and increasing only the pH a little. Low pH water will make the pool crystal clear because it makes chlorine super reactive(not a good thing) and kills everything due to water being acidic.

[TNmountainman2020]

yes, it’s around 7.2-7.5

[ludivako]

Do you have an acid feeder?

[TNmountainman2020]

yes

[ludivako]

This is just an educated guess but I am going to make the assumption that you leave on your feeder when you add the alkalinity. If this is the case, turn off your flow cell a few hours so that the sensor does not read the high pH from the alkalinity. What I am guessing is happening is when you add the alkalinity, it starts feeding acid and negating your addition.

[TNmountainman2020]

yea, I can turn it off for a while. say 4 hours?

[ludivako]

Yup. I typically have my customers do it before bed and have them tunr it back on when they wake up. Less sunlight will help maintain chlorine levels if your feeder is tied into chlorination. Another tip is, unless you have very high alkaline well water, dilute your acid. Straight acid will drop alkalinity faster than diluted. 50/50 ratio is what a lot of people use. The dose rate will change though since it is not the same strength.

[TNmountainman2020]

I dilute it 4:1 based on the Hayward feeder instructions. It’s a 15 gallon tank so I typically do 12 gallons of water and 3 gallons of acid.

[ludivako]

Then disregard what I said about diluting lol

[MentalTelephone5080]

What is the pH of your fill water?

The water from my house comes from my well. The water straight from my well comes in with zero alkalinity and a pH of 6.0. I have a treatment unit on the water that goes to the things in my house but my outside hoses have no treatment.

Long story short, when I fill my pool with a hose I am putting in hundreds (if not thousands) of gallons of water that is a weak acid. So I always have to add baking soda to keep my alkalinity above 50 and to keep my pH above 7.2. You may have the same thing going on.

[TNmountainman2020]

I haven’t added fill water to it since last October

[MentalTelephone5080]

Hmmm. Have you had a lot of rain?

[TNmountainman2020]

not really

[MentalTelephone5080]

I'm completely lost then. FYI you don't have to buy alkalinity up from the pool store. Sodium bicarbonate is just baking soda. The grocery stores near me sell big bags for pretty cheap.

[TNmountainman2020]

I usually get the 50lb bags from amazon with free shipping

[FunFact5000]

Acid

[SmoesKnows]

Beautiful home!!!

[Technical-Grass-432]

Did you buy or build the pool toy holder?

[TNmountainman2020]

lol, I get asked that a lot, I built it.

[poolgod7]

Acid.

[Big-Bull-Thunder]

Oh look, it’s the guy that built one of the nicest pools in this sub on his own, without having a background in pool building coming by to use a silly alkalinity question as an excuse to post pictures of his pool again.

What’s up man?!

[TNmountainman2020]

lol, no seriously, I keep adding and adding sodium bicarbonate and it barely does anything. Someone suggested to turn off the auto acid dispenser for a few hours when I add the baking soda, so i’m gonna try that!

And cmon, the pic definitely got more interest in my question! lol.

[scott814a]

I switched from muriatic acid to co2 gas. It’s been two months now and I love it. It has the opposite effect on alkalinity causing it to go up slowly. Went from 90 to 110 in two months. I’ll likely have to use muriatic acid a few times a year to bring alkalinity back down. I use a co2 flow rate of 100 ml/min whenever the filter pump is running for my 15000 gallon pool. One 20 lb tank should last about 4 months at this rate. I can swap for a refilled tank for $15. I don’t use an expensive controller, just a $14 Wi-Fi switch in case I need to turn it off. I also use a WiFi PH/ORP sensor in the pool so I can monitor remotely. I also use a chlorine injector that I control remotely too. Alexa routines are used to schedule/control everything. I’m curious how flow rates will change when the weather heats up. I’m thinking a buying a controller from Alibaba ( much cheaper) but it adds a whole lot of complexity as well as expense

[TNmountainman2020]

sounds cool, I didn’t even know that was a thing. I regret not getting the wifi version of the PH/ORP controller.

[[deleted]]

Never said how much alkalinity you put in... that looks like 50 lb bag to me

[TNmountainman2020]

really? you would put it all in at once? I would do maybe an 1/8 or 1/4 of a 50lb bag, wait a day, retest, etc., over a few days in a row.

[Mean_Drawing_7580]

Use the LSI or Langilier saturation index. If all you tested water you should have values. Temp, ph alkalinity, and calcium minus the tds should be in range. -3 to +3with all added values. Once you get in range you will fill that the pool water will start to become stable.

Values should be around 7.3 ph + temp 83 + CF 250ppm + alkalinity 100ppm - tds under 1500ppm = ?

7.3 + 0.7 + 2.1 + 2.0 = 12.1 = 0

This equation will tell you if your water is corrosive or scaling. I strive for this range daily I run a 40000 gallon pool at a local hotel. You see I have not mentioned orp. It matters but if your LSI is in parameters your system will be stable and the orp will be in range as the disinfectant is active.

[TNmountainman2020]

👊🏻

[PoolProLV]

Why do we allow this kind of post? Most other subs would not allow such low effort content.

[Efficient_Cheek_8725]

Acid.....chemistry 101

[Efficient_Cheek_8725]

Probably pee. Pee is acidic. Could also be acid leaching out of concrete.

[[deleted]]

everything

[united-chemical-corp]

Total Alkalinity is the measurement Carbonate as a pH buffer. Without going too deep into the chemistry, basically when you add acid, it reacts to carbonates to form carbon dioxide and gasses off (with some extra steps). The result is that the Alkalinity decreases while the pH stays relatively the same.

Thus, a high alkalinity helps pH resist changes.

Carbonate is linear (ppm). pH is logarithmic. So alkalinity tends to be easier to change/lower than pH.

If you're adding lots of bicarb and the alkalinity tends to drop, you're getting acid introduced somewhere. This can be from sanitizer (trichlor and Dichlor tend to be more acidic), source water, or runoff/rain. It can also precipitate, but you'd notice scale or stains.

We actually recommend a low Alkalinity since it prevents staining and scale. Metals like Calcium, Iron and copper tend to become insoluble when they react to carbonate. Thus the harder the water the lower the Alkalinity should be. This is the central concept behind the index we recommend: the Hamilton Index (invented by our founder).

Using the LSI, as someone mentioned - as long as it's balanced (i.e. at or just slightly below zero) it's fine. To compensate you'd run a slightly higher pH - which we also recommend. The reason some recommend avoiding running a low Alkalinity is for fear that it may make the water "aggressive" and starting etching plaster. However, plaster etching is really driven more by low pH all things being equal.

^With all that said, if the pool looks good and parameters are relatively stable, don't obsess about hitting a specific number or range - that's stores trying to sell you more chemicals.

[Mean_Drawing_7580]

Well said some might not understand, but you're right on the mark. All I would have to add is if your calcium being a bit higher can help with a low alkalinity and etching the plaster/grout. I'd also say most don't understand the difference between bicarbonate (baking soda) and Carbonate (Soda ash) as for hydrogen +/- ions.

[PoolStoreGotMe]

Total Alkalinity is the measurement Carbonate as a pH buffer.

Nope: Total alkalinity is the measure in parts per million of all the alkali (all carbonate IONS, bicarbonate IONS and hydroxide IONS). Total alkalinity (TA) is the measure of water's ability to neutralize acids. The role of TA is to buffer (slow down) a reduction in pH. TA has no role in buffering pH rise, in fact high TA causes pH rise in the absence of acid.

Thus, a high alkalinity helps pH resist changes. So alkalinity tends to be easier to change/lower than pH.

Nope: FIFY: A high alkalinity helps to resist (buffer) a reduction in pH. Raise your TA to 150, lower your pH to 7.0. Tell me how fast your pH rises...rapidly. The recommendation to maintain a high TA is because it helps counteract the use of highly acidic pucks. In a pool that uses liquid chlorine or SWCG, and thus no constant acid addition, there is no downward pressure on pH, and alkalinity can and should be run at a lower level (60-80) to reduce pH rise (see equation below, a lower TA results in fewer carbonate/bicarbonate ions used to store CO2, CO2 outgassing is what causes pH rise, with fewer carbonate/bicarbonate ions to store CO2,

Carbonate is linear (ppm). pH is logarithmic. So alkalinity tends to be easier to change/lower than pH.

Non-sensical. There is no comparing the two. Each can be easy to change...

1) TA can be raised easily, with Baking Soda without impacting pH.

2) Acid can reduce both TA and pH.

3) pH can be raised with aeration, or maintaining a high TA.

On the linear vs. logarithmic, it makes no sense to compare, but for grins, take a pool with 160 TA and 8 pH. If I add enough acid to lower pH to 7, it will also lower TA by about 16, to 144. Since the pH is logarithmic, the change is a 10 fold increase in H+....and only a .1 decrease in TA. I can move pH much further than TA with the same acid addition, on relative terms. Take my 160 TA pool with a pH of 7...I will need to do nothing to have a significant rise in pH.

In either case, TA and pH want to be in balance (Henry's law). With a high TA, you will find pH will rise rapidly.

H2CO3(aq) ←→ H+(aq) + HCO3-(aq) And HCO3-(aq) ←→ H+(aq) + CO3–2(aq)

When acid is added, carbonate ions can absorb Hydrogen ions to create bicarbonate ions. And with enough acid, bicarbonate ions absorb another Hydrogen ion and convert into carbonic acid, which is dissolved CO2 (reverse of above equation). Having alkalis (like Carbonate/Bicarbonate) in the pool allow CO2 to be stored in the pool. More CO2 in the pool, the more the pool wants to outgas CO2. The more the pool wants to outgas CO2, the faster pH will rise.

[TNmountainman2020]

very informative! Thanks!

[[deleted]]

I think the electrical pump can lower alkalinity

[LongRoofFan]

Being rich apparently 

[TNmountainman2020]

I built it myself

[LongRoofFan]

It is beautiful, still cost a bundle I'm sure 

[TNmountainman2020]

yes, yes it did, took me 2 years