Low low ph

[CinGA]

I need help and nothing I seem to do fixes my issues, so I'm really hoping you guys can give me some advice.  Please be patient as I outline all the things I did to screw up my 10 gallon tank, so you have all the facts.  

I had a perfectly well working 10 gallon tank with just a few small dwarf rasboras.  I decided I wanted to try my hand at caradina shrimp, since my neocaradinas were doing so well.  Since my tap water was naturally soft out of the tap, I thought I could skip the RO water and substrate and just add shrimp (mistake #1).  Needless to say they died.  Everyone on other forums told me I needed to be using RO water and remineralizing it, so I got a RO filter and SS GH+.  Starting using that.  For a month or so, all was good.  Then shrimp started dying.  Checked my parameters and learned my GH was at 10 dpGH because I had foolishly been topping off with remineralized RO water as needed instead of plain RO (mistake #2).  Lost a few shrimp but fixed that slowly over a couple of weeks.  Then one day I noticed my fish were looking abnormally pale, so I rechecked everything.  This time, instead of just using my API kit to test ph, I broke out a digital meter.  And learned my ph was incredibly low.  Low meaning 3.9. And obviously had an ammonia spike because the low ph killed off my biofilter.  Again reached out for advice on some forums and was told the problem was because I didn't add a buffering substrate originally.  (mistake #3).  So I added UNS controsoil.  

Here is my problem.  It's been almost a week and the ph isn't coming up much (it came up a tiny bit after I added the soil, but nothing since).  Of course I don't want it to come up really fast and kill my fish, but I'd have hoped to see some improvement after multiple water changes with remineralized RO water.  Here is where I'm getting confused.  I understand the substrate won't raise the ph, but the RO water should be neutral - around 7ph, correct?  Over the past week, I've changed well over 50% of the water in the tank (usually 15-20% at a time) with the RO water and I expected that the substrate would keep the ph from sinking, so my assumption was that the ph would slowly rise as I replaced the original low ph tank water with neutral RO water and the substrate kept the new water from sinking as the old had.  That has not worked.  If I can't get the ph up, I can't get the biolfilter restarted.  Of course, I'm also worried about the ammonia becoming toxic to the fish once I get the ph up as well, but I'm dosing with Seachem Prime daily to try and prevent any issues, as well as installing an ammonia removing pad in the filter.  

Current status:

Ph 4.4 (it's possible it could be off a little since I'm out of calibration solution - I have some ordered and should get soon)

Ammonia 1.5 ppm

Nitrites 0

Nitrates 20 ppm

Tank is planted, but most plants did not fare well with the low ph so I only have a couple of annubias in there at the moment.  I have ordered new plants, but I worry they will die in the low ph as well.

I added UNS Controsoil substrate.  I admit I took an easy way out and just added roughly an inch on top of my existing inert gravel rather than stripping it all bare and restarting.  The gravel was low anyway so I didn't mind building the substrate up a little.  

The only stock at the moment is 7 dwarf rasbora and a few surprising pest snails that have managed to stay alive.  

 

Any advice on how to fix this disaster of a tank? I really would like to have it stocked with my rasbora and some blue bolt shrimp, if I can just get it working correctly again.

 

[Mmiller2001]

I don't believe your pH is that low and lower pH does not stop the bio filter. That's out right wrong. I would wait for the calibration solution before making any decisions to change water chemistry. If the ammonia is actually that high, just keep up on water changes until you receive the solution. What's the KH of the tank?

[CinGA]

KH should be 0-1 since I am using RO water remineralized with SS GH+. Last I checked, that’s what it was but I obviously don’t check it that often since there shouldn’t be any. 
 

if my bio filter was working, then I shouldn’t have that much ammonia, right? And it was working before I made all these mistakes and screwed it all up. This tank is over a year old and was working up until a month or so ago. 

[Mmiller2001]

Sounds like something else is causing the ammonia. Some active substrates leach ammonia for a while. Keep up water changes until the calibration solution has arrived. Personally, I've thrown away all my pH pens and use a liquid pH kit from my local hydroponics store.

I run my tank at 0dKH and inject CO2 which drives my pH to 4.8.

[nabokovfan87]

On 6/26/2023 at 8:39 AM, CinGA said:

I thought I could skip the RO water and substrate and just add shrimp (mistake #1).

The type of shrimp definitely plays a role here. Sometimes you need RO water for consistency sake, sometimes it is not critical of your tap has specific traits.

On 6/26/2023 at 8:39 AM, CinGA said:

Needless to say they died.  Everyone on other forums told me I needed to be using RO water and remineralizing it, so I got a RO filter and SS GH+.  Starting using that.  For a month or so, all was good.  Then shrimp started dying.

This is very much incorrect! Unfortunately.

On 6/26/2023 at 8:39 AM, CinGA said:

Checked my parameters and learned my GH was at 10 dpGH because I had foolishly been topping off with remineralized RO water as needed instead of plain RO (mistake #2).  Lost a few shrimp but fixed that slowly over a couple of weeks.  Then one day I noticed my fish were looking abnormally pale, so I rechecked everything.

This goes back to what type of shrimp, but it depends on how sensitive they are and how you're performing those water changes. Some can handle normal water changes like any sort of community tank while others need the water added back drip by drip.

On 6/26/2023 at 8:39 AM, CinGA said:

Again reached out for advice on some forums and was told the problem was because I didn't add a buffering substrate originally.  (mistake #3).  So I added UNS controsoil.  

This isn't a mistake, but moreso just a mix of everything above and the complex nature of using an active substrate. It changes over time, especially initially. You would level things out by using water changes and allowing the substrate to absorb minerals and release organics (that's why the PH drops really hard initially).

On 6/26/2023 at 8:39 AM, CinGA said:

Any advice on how to fix this disaster of a tank? I really would like to have it stocked with my rasbora and some blue bolt shrimp, if I can just get it working correctly again

I will like the above YouTube creator and this video in particular. He has a ton of content on caridina shrimp as well as tank setup, substrate setup, and issues that you're facing.

For the short term, remove the shrimp and keep them in a bucket with some plants or decor and an air stone. You can add some substrate to that bucket, but it shouldn't be mandatory. Ultimately, they will be in there short term while you fix the tank.

The tank will take about a few weeks, maybe less to stabilize itself. The way you do this is via water changes.  At first you're talking near daily water changer for a week, then a few through the next week, and then weekly changes.  This is not great for the shrimp and it's something that causes a lot of stress.

Second thing you have to handle is the pH of the fish balanced with the care of the shrimp.  The shrimp want stability!!!!! If the PH is low, that's not really a bad thing. For some fish though once you get below 6.5 it can be difficult.  As I haven't kept them personally, refer to MSTs videos, I cannot say if that is ok for the caridina species long term.

Ultimately, the best setup is a shrimp only tank to meet that care need and a setup with fish only while the colony of shrimp can establish itself. This video points to a playlist  about shrimp basics, but the first one linked below is all about fish and shrimp together.

 

On 6/26/2023 at 9:24 AM, Mmiller2001 said:

Sounds like something else is causing the ammonia.

UNS isn't known to leech a ton of ammonia.

[TOtrees]

One thing to consider is that pH is logarithmic. Meaning that each whole number is 10x more acid or alkaline than the next whole number, eg 6 is 10x more acidic than 7, and 5 is 100x more acidic than 7. This means that you need to change more water to shift the pH than you think (not taking into account the things going on in the tank that cause pH to also shift). 

[CinGA]

On 6/26/2023 at 12:59 PM, TOtrees said:

One thing to consider is that pH is logarithmic. Meaning that each whole number is 10x more acid or alkaline than the next whole number, eg 6 is 10x more acidic than 7, and 5 is 100x more acidic than 7. This means that you need to change more water to shift the pH than you think (not taking into account the things going on in the tank that cause pH to also shift). 

Ooh, that's a good point and something I hadn't considered.   And that would certainly explain why it's been so much slower to change.  

No shrimp to remove, sadly.  The last of them died right as I was trying to get them out to do the substrate change - which I kind of expected.  They were so stressed by that point, I knew any kind of change would probably finish them off, and it did.  But on the one hand, at least that's good as it means I have more ability to do what's necessary to fix the tank.  

So it sounds like I just need to keep on as I have been with daily water changes and it will just take some time.  That's fine, I can work with that as long as I have some hope that I'm on the right track to fix it.  

 

Thank you all.  I'd had such an easy time of it with my cherry shrimp, I hadn't really prepared fully for the learning curve involved with caradina shrimp.  I think once I get this all straightened out, it should run really well.  I hope so, anyway.  

 

 

[nabokovfan87]

On 6/26/2023 at 10:34 AM, CinGA said:

Thank you all.  I'd had such an easy time of it with my cherry shrimp, I hadn't really prepared fully for the learning curve involved with caradina shrimp.  I think once I get this all straightened out, it should run really well.  I hope so, anyway.  

Definitely. Check out a bunch of Mark's videos. He's the best source I know of. He's got a video for literally everything and has a website to try to get all of that stuff easier to find.

[Lennie]

On 6/26/2023 at 6:39 PM, CinGA said:

I understand the substrate won't raise the ph, but the RO water should be neutral - around 7ph, correct?

False. My Ro water has exactly 6.0 ph.

it depends on your system I guess. It is usually between 5 to 7 based on what you have I believe.

Ideally, you should take some water in a cup, aerate it with an airstone, and after some good amount of time, test the water again to see what you actually get as ph from your RO once it is aerated in the tank

On 6/26/2023 at 6:39 PM, CinGA said:

I added UNS Controsoil substrate.  I admit I took an easy way out and just added roughly an inch on top of my existing inert gravel rather than stripping it all bare and restarting.  The gravel was low anyway so I didn't mind building the substrate up a little.  

I personally dont find adding aquasoil later on a good idea. Instead I use it from the start, and expect it to complete its high leechjng period and after parameters are stable and the tank is cycled m, then I add the fish. So your soil is probably leeching ammonia rn. The smallest tank size ive used aquasoil was 50 liters and with an established filter and lots of water changes, it took a while to clear all ammonia out with tropical aquasoil. Your probably leech less in general but might be the reason why you are reading ammonia(or ammonium).

btw normal substrate+ 1 inch extra aquasoil would n top, equipments, plants and all, you cut a lot from a 5g tank water size. 5g is already pretty small. i would try to find some way to fix this problem. 
Even my 50 Liter betta tank feels small with a very thin layer of substrate and a few baby endlers. So yours is smaller than the half size of my betta tank without such thick substrate already.

Please dont get it wrong. I just keep lots of bettas and they love swimming and 10g is bare minimum in my opinion. So feel like we need to increase the potential swimming space on what you have on your hand to make your betta feel comfier. I kept this guy in 42g too and he was crazy happy

Btw, Ive just remembered.

You are gonna need a water around 7 ph for healthy bettas. Ph both on higher or lower end won't be good. The middle is always better because bettas tend to have health issues pretty easily from what I see online. Thankfully I haven't faced any on 8 ( 3m, 5f) I have, except one female in the picture being a lil eggbound.

Edited June 26, 2023 by Lennie

[CinGA]

Couple of thoughts. 
 

I have a 10g not a 5 gallon. I don’t have a betta - I have seven very tiny dwarf rasboras which are the smallest fish I have ever seen personally. The tank is very lightly stocked I think. 
 

I would have added the controsoil first if I’d known what I was going to do with this tank when I set it up. It had been cycled for a year before I decided to add shrimp. I am adding active substrate from the start on my newest tank. It was not the cause of the ammonia - that existed before I added the substrate, presumably once the ph crashed. I know some of the ammonia now though is from the soil. 
 

My RO water actually comes out of the system at close to 8 but after aerating for 24 hours, it usually sinks down to 6.5 or so, so I absolutely agree on that front - I should have specified that it’s around 7.0, not that exactly. 
 

I think you can see from the pic the substrate isn’t too bad. (I’m actually mid water change so the water isn’t all the way to the top yet). The gravel was actually pretty thin to begin with - below an inch in several area. The plants are a bit sparse but I do have some on the way this week. 

[Lennie]

On 6/26/2023 at 10:16 PM, CinGA said:

Couple of thoughts. 
 

I have a 10g not a 5 gallon. I don’t have a betta - I have seven very tiny dwarf rasboras which are the smallest fish I have ever seen personally. The tank is very lightly stocked I think. 
 

I would have added the controsoil first if I’d known what I was going to do with this tank when I set it up. It had been cycled for a year before I decided to add shrimp. I am adding active substrate from the start on my newest tank. It was not the cause of the ammonia - that existed before I added the substrate, presumably once the ph crashed. I know some of the ammonia now though is from the soil. 
 

My RO water actually comes out of the system at close to 8 but after aerating for 24 hours, it usually sinks down to 6.5 or so, so I absolutely agree on that front - I should have specified that it’s around 7.0, not that exactly. 
 

I think you can see from the pic the substrate isn’t too bad. (I’m actually mid water change so the water isn’t all the way to the top yet). The gravel was actually pretty thin to begin with - below an inch in several area. The plants are a bit sparse but I do have some on the way this week. 

Ah, my bad.

Ive just woken up from a nap and checked so many topics to help on bed. I probably got confused with someone else having betta as their stock with a different question. Sleepy lennie brain 🙂  Sorry.

 Now I gotta go find where I read that 🤣

Contrasoil is usually known to leech for a shorter period and lower amounts from a few people I've heard of. Especially compared to ones like ADA or Tropica. While waiting for plants, I would try to get rid of that algae problem. Have you tried RR on them? Also their rhizomes are not in the substrate right? I would also take your decoration and rock out and clean it from algae rn before setting up everything with the new plants.

Are you sure those floating plants are alive? Decaying plant matter also contributes to the ammonia. If they are dead, I would throw them away. I once had a salvinia order which almost all died except two tiny pieces. Those lil two tiny green pieces ended up recovering and growing.

 

When I wanted to reach to my bettas desired 7 range ph, I was adding small bottle of dechlorinated tap water with water changes and it didn't take much for me to reach the desired ph, as my tap is 8.0 ph and 20 kh. 

What's your tap water parameters are like? You said soft water so low gh, but what about kh and ph?

[CinGA]

I figured that’s what it was. No worries!  I could use a nap myself. 
 

My tap actually has zero KH. Or as low as I can test anyway - it always turns yellow with the first drop. But the PH out of the tap is actually really high - over 8. That’s how I learned (the hard way naturally) that I had to drip the water back in slowly. But of course, with zero KH, it sinks if I let it sit out. That’s why I originally thought I could do without RO water and active substrate - I just thought adding a little remineralizer to get GH where it needed to be was all I would need to do. 
 

What is RR? I’d love to get the algae off. I’ve been working on it but not having much luck. I probably do need to get rid of the salvinia - it went gang busters in my other tank but is not doing at all well here. I keep hoping it will turn around but I guess it’s a lost cause. The annubias is not in the substrate - I have plant weights on them and just dropped them down. The lily bulb is half in - it was doing well until the tank went crazy. 

[Lennie]

On 6/26/2023 at 10:42 PM, CinGA said:

I figured that’s what it was. No worries!  I could use a nap myself. 
 

My tap actually has zero KH. Or as low as I can test anyway - it always turns yellow with the first drop. But the PH out of the tap is actually really high - over 8. That’s how I learned (the hard way naturally) that I had to drip the water back in slowly. But of course, with zero KH, it sinks if I let it sit out. That’s why I originally thought I could do without RO water and active substrate - I just thought adding a little remineralizer to get GH where it needed to be was all I would need to do. 
 

What is RR? I’d love to get the algae off. I’ve been working on it but not having much luck. I probably do need to get rid of the salvinia - it went gang busters in my other tank but is not doing at all well here. I keep hoping it will turn around but I guess it’s a lost cause. The annubias is not in the substrate - I have plant weights on them and just dropped them down. The lily bulb is half in - it was doing well until the tank went crazy. 

I had very bad luck with salvinia shipment so I feel you.

However, my frogbits and water lettuce arrived in much better condition. Maybe you can give them a try when you settle everything down.

 

For RR, you can use this to get rid off from your current algae problem as well as to dip your new upcoming plants! Here is the detailed topic:

Here is the website:

https://reverserespiration.com/ 

Edited June 26, 2023 by Lennie

[tolstoy21]

On 6/26/2023 at 11:39 AM, CinGA said:

I understand the substrate won't raise the ph, but the RO water should be neutral - around 7ph, correct? 

RO water is neutral in theory, meaning nothing has influenced it yet. But the moment it's mixed with any kind of buffer --alkaline or acidic -- it will swing quickly towards a direction determined by the amount of buffer. If you put RO water in a tank with a Ph of 4, it will drop. It wont raise the Ph towards 7. It will measure 7 initially because it's currently neither acidic or alkaline. It's kind of a blank slate waiting to be acted upon. 

Edited June 26, 2023 by tolstoy21

[tolstoy21]

To quote a quick article I grabbed of the interwebs - 

Quote

Reverse osmosis water is nearly pure water with a PH of 7. Reverse osmosis is a filtration method that removes more than 99% of all the contaminants in water.

The result is nearly pure water, which has neutral pH of 7. But if it’s exposed to air, RO water drops down to an acidic pH range of 5 – 5.5. Why? Pure water is very hungry. it actually grabs CO2 right out of the air! Within about an hour, a glass of pure RO water can drop from a pH of 7 down to a pH of 5.5 or lower and become acidic water. Alkaline water has a pH of greater than 7, so reverse osmosis water is not alkaline water. To alkalize it, you have to add calcium and other minerals to it.

Source -- https://www.123filter.com/ac/why-reverse-osmosis-water-is-acidic

[Mmiller2001]

On 6/26/2023 at 1:01 PM, Lennie said:

False. My Ro water has exactly 6.0 ph.

it depends on your system I guess. It is usually between 5 to 7 based on what you have I believe.

Ideally, you should take some water in a cup, aerate it with an airstone, and after some good amount of time, test the water again to see what you actually get as ph from your RO once it is aerated in the tank

My understanding is zero TDS water is neutral 7 always, but can't be tested without very sophisticated tools. And an accurate pH can never be taken, without these sophisticated tools, until TDS has been added. I believe a TDS of 50ish will then allow a true pH to be tested using our generic tests.

Edited June 26, 2023 by Mmiller2001

[Lennie]

On 6/26/2023 at 11:18 PM, Mmiller2001 said:

My understanding is zero TDS water is neutral 7 always, but can't be tested without very sophisticated tools. And an accurate pH can never be taken, without these sophisticated tools, until TDS has been added. I believe a TDS of 50ish will then allow a true pH to be tested using our generic tests.

I see

The last time the water guy was over, he tested and my RO tds test read 24. So whatever that 24 is coming from, it may be affecting the ph you say?

I have both water softener in the whole house + RO water. If it still reads this way, is it possible to read the perfect 7 with 0 tds? Seems kinda hard. My tap with water softener already reads 0 gh, however has a tds of 370. So RO system cuts that part from 370 to 24. But gh reads 0 both ways

[Mmiller2001]

On 6/26/2023 at 2:25 PM, Lennie said:

The last time the water guy was over, he tested and my RO tds test read 24. So whatever that 24 is coming from, it may be affecting the ph you say?

It definitely will affect pH, but such low TDS does make it difficult to get an accurate pH with our hobby level kits. I always ignore pH of my RO storage even after I mineralize and fertilize it. The only pH that matters is the tank pH when it mixes to higher TDS and Nitrification buffers the tank. 

[Galabar]

You should expect RO water to hit ph 5 - 5.5 after sitting out for a while (as it absorbs CO2)

https://www.123filter.com/ac/why-reverse-osmosis-water-is-acidic#:~:text=Reverse osmosis is a filtration,pH range of 5 – 5.5.

 

[Andy's Fish Den]

I have been using RO and RO/DI units for the last ten years or so being that I have kept reef and other saltwater tanks. Most, if not all units if they are only RO units will not give you pure water with a zero TDS. I have a top of the line Bulk Reef Supply RO/DI unit, and when the water comes out of the reverse osmosis membrane still has a TDS of anywhere from 1-15 depending upon what the TDS of the water entering the unit is, and how old all the sediment and carbon blocks are, then once it goes through the deionization part, it will be zero TDS. So, what I getting to is, if the water is not at a true TDS of 0, then whatever molecules are still in the water can be affecting the water and pH. As @tolstoy21stated above, that RO water will be neutral, and if it sits in an open container, the pH will drop. 

Personally, I would quit chasing pH, just do water changes with your tap water, let the tank balance out, and there will be a lot less headaches for you. 

[tolstoy21]

On 6/27/2023 at 6:51 AM, Andy's Fish Den said:

I have been using RO and RO/DI units for the last ten years or so being that I have kept reef and other saltwater tanks. Most, if not all units if they are only RO units will not give you pure water with a zero TDS. I have a top of the line Bulk Reef Supply RO/DI unit, and when the water comes out of the reverse osmosis membrane still has a TDS of anywhere from 1-15 depending upon what the TDS of the water entering the unit is, and how old all the sediment and carbon blocks are, then once it goes through the deionization part, it will be zero TDS. So, what I getting to is, if the water is not at a true TDS of 0, then whatever molecules are still in the water can be affecting the water and pH. As @tolstoy21stated above, that RO water will be neutral, and if it sits in an open container, the pH will drop. 

Personally, I would quit chasing pH, just do water changes with your tap water, let the tank balance out, and there will be a lot less headaches for you. 

Yup. Same. My water comes from the RO membrane with a TDS of about 12 with my unit, and is then further cleaned up the DI resins that strip the remaining 'stuff' from the water.

@Lennie @CinGA What the TDS of the water is post-membrane is variable depending on a number of factors that increase or decrease what is known as it's 'rejection' rate. These include the TDS of the water going in, membrane age, water pressure to the membrane, etc.

If you want to know if that remaining TDS has an impact on PH, just test it's KH.

 

[Lennie]

On 6/27/2023 at 5:02 PM, tolstoy21 said:

If you want to know if that remaining TDS has an impact on PH, just test it's KH.

My tap( 0 gh due to softener, 8.0 ph) has 20ppm kh;  but my RO, which has 24-25 tds, has 0 kh. Reads exactly 6.0 ph

[Galabar]

Over here in the Pacific Northwest (Bellevue, WA), my water is about 20-30 TDS out of the tap.  Great for some things, but needs "remineralization" for most things... 

[CinGA]

On 6/27/2023 at 6:51 AM, Andy's Fish Den said:

I have been using RO and RO/DI units for the last ten years or so being that I have kept reef and other saltwater tanks. Most, if not all units if they are only RO units will not give you pure water with a zero TDS. I have a top of the line Bulk Reef Supply RO/DI unit, and when the water comes out of the reverse osmosis membrane still has a TDS of anywhere from 1-15 depending upon what the TDS of the water entering the unit is, and how old all the sediment and carbon blocks are, then once it goes through the deionization part, it will be zero TDS. So, what I getting to is, if the water is not at a true TDS of 0, then whatever molecules are still in the water can be affecting the water and pH. As @tolstoy21stated above, that RO water will be neutral, and if it sits in an open container, the pH will drop. 

Personally, I would quit chasing pH, just do water changes with your tap water, let the tank balance out, and there will be a lot less headaches for you. 

I'm not trying to chase ph.  I'm trying to get it high enough that I can restart the cycle in that tank.  Frankly, I don't care right now if it's 6, 6.5, 7 or 7.5 or somewhere in between.  I just want it high enough that the biofilter will work again.  Which....doesn't seem to be happening.  I did another water change yesterday - about 50% - and I swear the ph is no higher than before.  Still no nitrites so no bacteria growing (not surprising when the ph is below 5). 

I suppose I can start using tap instead of remineralized RO for the water changes, and then just do a couple of massive water changes to RO water when I'm ready to add the shrimp and the tank is stabilized.  I'm not sure I understand how that will help though - if the RO water can't stay at a high enough ph to maintain a biofilter now, why will it be able to later?

On 6/26/2023 at 6:16 PM, Galabar said:

You should expect RO water to hit ph 5 - 5.5 after sitting out for a while (as it absorbs CO2)

https://www.123filter.com/ac/why-reverse-osmosis-water-is-acidic#:~:text=Reverse osmosis is a filtration,pH range of 5 – 5.5.

 

Ok....but then how do shrimp tanks with the buffering substrate maintain a ph of 6-6.5?  I'm not trying to argue - I truly don't understand how the RO/buffering substrate combo is supposed to work, which is the source of a lot of my trouble, I suspect.  

[Galabar]

What is the API test kit saying?  It may be the case that you are getting inaccurate results from your meter, especially if you haven't calibrated it.

The API test kit should be fine within a certain range...

As for an "active substrate", I'm guessing that it has an acid buffer in it (as opposed to a basic/alkaline buffer):

https://www.chemguide.co.uk/physical/acidbaseeqia/buffers.html#:~:text=An acidic buffer solution is,and sodium ethanoate in solution.

https://www.seachem.com/acid-buffer.php#:~:text=Acid Buffer™ is a,used with Alkaline Buffer™.

It will react with any carbonates added to the water.  This keeps to pH down.  However, at some point, it can be exhausted.  So, you need to use RO water to extend its lifetime.

 

Edited June 27, 2023 by Galabar