What’s causing my pH spike?

alexk77

Member
I’m the type of person who tests their water very frequently. I just got back from Easter holidays, i’ve had some friends fish sit for me while i was gone for 4 days. They were only supposed to feed them, which they did but are not aquarium hobbyists and do not know how to test water, and they shouldnt have to while i’m gone on vacation. So i came back, did a full water test and everything looked great except for my pH.
Typically, my pH stays around 7.4, sometimes i catch it at 7.8 but that’s usually when i also see high nitrates and when i do a water change to bring all that back down. To my surprise though, my pH has spiked up to 8.2. Everything else in my test was normal:
Ammonia: 0
Nitrite: 0
Nitrate: 5ppm
I’m planning on doing a water change to bring the pH back down to normal, but what the heck caused the spike? I’ve never had this happen before.
I’d like to note also that i’ve had a bit of a brown algae infestation that i’ve been trying to deal with, i’ve got a pleco but he just can’t seem to keep up.
my substrates include aquarium gravel and lava rock spread out because it doesn’t tend to change pH, is great for bacterial growth and honestly i just think it looks cool.
I’ve got a big seashell also as decor, i’m not sure whether its real or not but I think that’s a pretty big culprit as I looked it up and found that some shells do raise pH? Even though it’s strange that i didn’t see this spike earlier.
Please help me figure this out! :/
 
Best Answer - View Chanyi's answer

Broggy

Member
do you dose the tank with chemicals? the shell could be doing this, but shouldn't cause large fluctuations.

what are the water parameters straight from your tap?
 

SouthAmericanCichlids

Member
Maybe one of your friends accidentally dropped something in without realizing.
 

StarGirl

Member
It is probably the shell. It may have just started to leech. Have you ever tested your tap water then set some out for 24 hours and test it again to see if it changed after it gassed off?
 

StinkyLoaf

Member
The spike seems to have happened roughly around the same time your friends were babysitting the fish. There’s nothing else to suggest why the spike has happened so it was most likely them who caused it to rise somehow...
 
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alexk77

Member
Broggy said:
do you dose the tank with chemicals? the shell could be doing this, but shouldn't cause large fluctuations.

what are the water parameters straight from your tap?
I never dose with chemicals. I also don’t use tap water for my tank, i use reverse osmosis water from a local water clinic. That water has a pH of about 6.8.
I guess i also forgot to mention that one of my fish died while i was gone (a dwarf gourami who already looked like he was on his way out. He had symptoms of DGD so i believe that’s what took him, sadly), usually that raises ammonia but could that also raise pH? there was no ammonia present in my test.
SouthAmericanCichlids said:
Maybe one of your friends accidentally dropped something in without realizing.
It could’ve been one of my fish sitters. They could’ve put their fingers in the water without washing their hands beforehand, among other things I’ll have to check with them.
StarGirl said:
It is probably the shell. It may have just started to leech. Have you ever tested your tap water then set some out for 24 hours and test it again to see if it changed after it gassed off?
I can remove the shell, do a water change and see whether the water spikes again. if it doesn’t, it was probably the shell.
As i said earlier i don’t use my tap water, i use reverse osmosis.
 

Cherryshrimp420

Member
Well that explains it. RO water has no KH so any seashell you put in will quickly raise the pH.

Fish should not be kept in RO water at all, it needs to be re-mineralized first
 

Broggy

Member
alexk77 said:
I never dose with chemicals. I also don’t use tap water for my tank, i use reverse osmosis water from a local water clinic. That water has a pH of about 6.8.
I guess i also forgot to mention that one of my fish died while i was gone (a dwarf gourami who already looked like he was on his way out. He had symptoms of DGD so i believe that’s what took him, sadly), usually that raises ammonia but could that also raise pH? there was no ammonia present in my test.

It could’ve been one of my fish sitters. They could’ve put their fingers in the water without washing their hands beforehand, among other things I’ll have to check with them.
anything could have happened especially because your fish sitter was taking care of them. not that they werent trustworthy, but they could have done something wrong without knowing.

i have no idea why this is happening, sorry to be unhelpful.
 
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alexk77

Member
Cherryshrimp420 said:
Well that explains it. RO water has no KH so any seashell you put in will quickly raise the pH.

Fish should not be kept in RO water at all, it needs to be re-mineralized first
Was not aware that RO water had to be re-mineralized. Only thought it was bad to put distilled water in so i will take note of this. I do use a bacterial conditioner to maintain the tank on a weekly basis but i’ll look for some RO water conditioner.
What do you mean by “quickly” when it comes to shells raising pH? My tank has been running for over 2 months with fish in it. I haven’t seen a spike like this. Is the shell just starting to leech now? as stargirl said? My fish are behaving very healthy other than the dwarf gourami who died of DGD.
Your reply kinda shocked me, but i’m glad you informed me of this. I thought RO was the best thing to use for aquariums due to their lack of unhealthy minerals, as that’s what my research had told me before i joined fishlore
 

Cherryshrimp420

Member
alexk77 said:
Was not aware that RO water had to be re-mineralized. Only thought it was bad to put distilled water in so i will take note of this. I do use a bacterial conditioner to maintain the tank on a weekly basis but i’ll look for some RO water conditioner.
What do you mean by “quickly” when it comes to shells raising pH? My tank has been running for over 2 months with fish in it. I haven’t seen a spike like this. Is the shell just starting to leech now? as stargirl said? My fish are behaving very healthy other than the dwarf gourami who died of DGD.
Your reply kinda shocked me, but i’m glad you informed me of this. I thought RO was the best thing to use for aquariums due to their lack of unhealthy minerals, as that’s what my research had told me before i joined fishlore
The minerals are actually essential to plant and livestock growth...its more of long-term effect so eventually it will impact your tank.

Look for re-mineralizers, which are not the same as water conditioners. Basically look for products to raise the GH and KH. They are usually sold as separate products but some brands have them combined.

The easier alternative is to just use tap water depending on your tap water parameters.

Water without any buffers (KH) will have large pH changes any time you put something acidic or basic in it. In your case it may be the seashell, or it could be other rocks, decor etc. Hard to say exactly which one, but just know that water without KH will experience pH swings very easily.
 
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alexk77

Member
Cherryshrimp420 said:
The minerals are actually essential to plant and livestock growth...its more of long-term effect so eventually it will impact your tank.

Look for re-mineralizers, which are not the same as water conditioners. Basically look for products to raise the GH and KH. They are usually sold as separate products but some brands have them combined.

The easier alternative is to just use tap water depending on your tap water parameters.

Water without any buffers (KH) will have large pH changes any time you put something acidic or basic in it. In your case it may be the seashell, or it could be other rocks, decor etc. Hard to say exactly which one, but just know that water without KH will experience pH swings very easily.
Alright, sounds great. Thanks for that amazing info
 
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alexk77

Member
Hey guys,
I went ahead and tested my tap water. I have done this before and the results are what had convinced me to go with RO water, but i had only tested the tap water initially and didn’t wait for the 24 hour gas off to happen. This was also when I was fairly new to testing water and taking water tests seriously, so I thought i’d do it again since i have more knowledge.
Initial tap parameters:
pH: 8.2
Ammo: 0.5ppm
Nitrite: 0
Nitrate: 0

Tap test after 24hr gas off:
pH: 8.0
Ammo: 0.5ppm
Nitrite: 0
Nitrate: 0

Due to the amount of ammonia present and the fairly high pH of my tap water, I was convinced I should use RO water. I also thought RO water was easier because i had no idea it needed re mineralizing. So obviously I have much more to learn, which leads me to ask if these are in fact appropriate tap water parameters or if it’ll be easier to use RO water? I want to use as little chemicals as possible of course.
 

ZachG

Member
The ph in my water is also 8.2, I don’t have any ammonia in mine although I’ve seen it in other’s as well. If you want to use it I would treat it with seachem prime, if your aquarium is well established it should have no trouble getting rid of the ammonium in time.
 

Chanyi

Member
100% RO water:

Target 0.5 - 1.0 degrees of KH using KHCO3 or K2CO3
25ppm Ca using CaSO4
10ppm Mg using MgSO4

Use to help determine the amount of each you will have to dose into your RO water prior to a water change.

This is the cheapest, easiest way to achieve those parameters with the least amount of products possible.
 
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alexk77

Member
P.S. I’m in the process of buying KH and GH tests as well as RO re mineralizer (and a new scrubber for that ugly brown algae). I’m waiting to do a water change until I get those things so i’m not adding more unmineralized RO water.
ZachG said:
The ph in my water is also 8.2, I don’t have any ammonia in mine although I’ve seen it in other’s as well. If you want to use it I would treat it with seachem prime, if your aquarium is well established it should have no trouble getting rid of the ammonium in time.
Does seachem prime also serve as water conditioner? or would i have to add an additional conditioner to get rid of the chlorine and chloramine?
My tank is well established and i’m planning on getting live plants to help with nitrates in the near future
Chanyi said:
100% RO water:

Target 0.5 - 1.0 degrees of KH using KHCO3 or K2CO3
25ppm Ca using CaSO4
10ppm Mg using MgSO4

Use to help determine the amount of each you will have to dose into your RO water prior to a water change.

This is the cheapest, easiest way to achieve those parameters with the least amount of products possible.
Alright, thank you for this! I’m assuming i can purchase those products at my local LFS, correct? or will they need ordering? Your directions confuse me a little lol, but that’s probably because i don’t have the products I need to understand what you mean. Will update when i get those in my hands!
 

StarGirl

Member
Prime is water conditioner you don't need another.
 

Chanyi

Member
alexk77 said:
Alright, thank you for this! I’m assuming i can purchase those products at my local LFS, correct? or will they need ordering? Your directions confuse me a little lol, but that’s probably because i don’t have the products I need to understand what you mean. Will update when i get those in my hands!

No Prime or any other water conditioner is need when using RO.

You only need 3 things:

KHCO3 or K2CO3 - Target 0.5 - 1.0 degree of KH using one of these products.
CaSO4 - Target 25ppm of Calcium using this product.
MgSO4 - Target 10ppm of Magnesium using this product.

Go to and type in the amount of water you change, select DIY, select the correct product you are using, select dose to reach target, type in your target value and hit calculate.

You likely cannot find these at a local fish store. Amazon, GLA and maybe Nilocg would have these. Just make sure they are 100% pure without any additives.

Dose them into your RO water before a water change, and make sure they are completely dissolved / premixed before you add the water into the tank.
 
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alexk77

Member
Chanyi said:
No Prime or any other water conditioner is need when using RO.

You only need 3 things:

KHCO3 or K2CO3 - Target 0.5 - 1.0 degree of KH using one of these products.
CaSO4 - Target 25ppm of Calcium using this product.
MgSO4 - Target 10ppm of Magnesium using this product.

Go to and type in the amount of water you change, select DIY, select the correct product you are using, select dose to reach target, type in your target value and hit calculate.

You likely cannot find these at a local fish store. Amazon, GLA and maybe Nilocg would have these. Just make sure they are 100% pure without any additives.

Dose them into your RO water before a water change, and make sure they are completely dissolved / premixed before you add the water into the tank.
Thanks for this, Sorry i’m replying so late. I keep my RO water in those big “culligan” bottles. I don’t remember how many gallons they are.
sorry, please be patient with me as i’ve never done this before... i’m wondering if salty shrimp KH/GH+ and seachem equilibrium and alkaline buffer will do the same as adding those minerals separately? It seems like those are the products i’m finding the most online for mineral restoration and maintenance, and many people are using them for their RO/DI water.
 
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alexk77

Member
Alright... I’ve decided i’m going to go with seachem equilibrium and alkaline buffer, since i’ve done some research on the forum and elsewhere it sounds like the easiest way to remineralize RO water. Even if it’s a little pricier, I’d rather do that then spend any more time finding each mineral individually. I plan on getting a tds meter with these products.. though I’m open to hearing alternate opinions always. I’m almost completely certain this is a good move to make. Seachem equilibrium raises GH, and alkaline buffer raises KH, which is what i understand i’m lacking in my tank and why my pH isn’t stable.
One final question: because adding these minerals will most likely change a few things chemistry wise in my tank, should i re acclimate my fish to this new water? I do have quite a few (about 15) in a 50 gallon aquarium. Will weekly water changes acclimate them with minimal stress?
PS thanks for everyone’s advice and help, i can’t express how appreciative i am!
 

Chanyi

Member
alexk77 said:
I plan on getting a tds meter with these products.. though I’m open to hearing alternate opinions always. I’m almost completely certain this is a good move to make.




https://www.amazon.ca/Home-Brew-Ohi...rds=potassium+carbonate&qid=1618506057&sr=8-6

There are the product needed if you haven't bought the Seachem stuff yet. 1lb of each should last you years and years.

also sells CaSO4 and MgSO4.

Amazon for the potassium carbonate / bicarbonate or look at brewing supply stores.

alexk77 said:
Seachem equilibrium raises GH, and alkaline buffer raises KH
Yes, that is correct. You should also be aware the Equilibrium adds a boat load of potassium.


alexk77 said:
One final question: because adding these minerals will most likely change a few things chemistry wise in my tank, should i re acclimate my fish to this new water? I do have quite a few (about 15) in a 50 gallon aquarium. Will weekly water changes acclimate them with minimal stress?
Mix them into your water prior to a water change. This requires you to pre-mix your water. You do not want to dump water into the tank and then add these products, Equilibrium isn't too bad, but the alkaline buffer will cause pH swings that can harm livestock.

I would start with small water changes, slowly increasing them over a few weeks until you are at you new parameter levels. This should slowly acclimate the livestock to your new parameters.
 
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alexk77

Member
Chanyi said:




Home Brew Ohio Potassium Bicarbonate, 1 Pound Capacity: Amazon.ca: Industrial & Scientific

There are the product needed if you haven't bought the Seachem stuff yet. 1lb of each should last you years and years.

also sells CaSO4 and MgSO4.

Amazon for the potassium carbonate / bicarbonate or look at brewing supply stores.



Yes, that is correct. You should also be aware the Equilibrium adds a boat load of potassium.




Mix them into your water prior to a water change. This requires you to pre-mix your water. You do not want to dump water into the tank and then add these products, Equilibrium isn't too bad, but the alkaline buffer will cause pH swings that can harm livestock.

I would start with small water changes, slowly increasing them over a few weeks until you are at you new parameter levels. This should slowly acclimate the livestock to your new parameters.
You have been so much help, so thank you for that and your patience with me And thanks for those links!! i literally couldn’t find those minerals anywhere i looked. I think i’m going to start of with the seachem products and see how they work, unless potassium is no good for water chemistry(?)
i’ve been getting anxious because i’m very overdue for a water change now, and going to my LFS for those products today will allow me to hopefully do a small water change today as well so i don’t have to wait any longer.
 

Chanyi

Member
alexk77 said:
I think i’m going to start of with the seachem products and see how they work, unless potassium is no good for water chemistry(?)
No worries. Eventually when you want more control over your parameters you can look into getting the individual products.

The extra potassium shouldn't hurt anything, just know that your TDS will be much, much higher using Equilibrium and Alkaline buffer as opposed to the individual products. Again, there should be nothing wrong with this, I'm simply keeping you informed of everything I can think of, that's all.
 
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alexk77

Member
Chanyi said:
No worries. Eventually when you want more control over your parameters you can look into getting the individual products.

The extra potassium shouldn't hurt anything, just know that your TDS will be much, much higher using Equilibrium and Alkaline buffer as opposed to the individual products. Again, there should be nothing wrong with this, I'm simply keeping you informed of everything I can think of, that's all.
I very much appreciate this. your knowledge has helped a ton! Might look into individual products when i’m not in such an urgent situation, they are super cheap. Thanks so much again
 
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alexk77

Member
Fish store didn’t have either seachem products.. looking into ordering tomorrow but i’m feeling desperate as my gravel looks disgusting due to being overdue for cleaning (my mollies and platys create a LOT of waste)
My dad was helping me look at some even faster solutions to my issue and he found crushed coral, typically used for cichlid tanks, will help. Is this true? could i use this? we have some from our trip to hawaii a few years ago so we’ll have to wash it out multiple times but it seems like my last resort at the moment. My apologies for coming back to this thread
P.S. to anyone wondering, my pH has dropped to about 7.8 since i took out the seashell.
Very frustrated at all my LFS for not having the basic products i need
 

Chanyi

Member
Crushed Coral will act as a buffer and add KH thus raise your pH. To what levels is anyone's guess.


It will likely add a little bit of GH but not enough to remineralize RO water up to 6 dGH or so.
 

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