Why water parameters changed?

Hi,

Not sure if I should be worried.

Yesterday I did a 25% water change and today I made some tests with Api drops test kit.

Jun 12 results:
pH: 7.8
KH: 10
GH: 11
Ammonia: 0 ppm
Nitrite: 0 ppm
Nitrate: 5 ppm

June 20 results:
pH: 7.4
KH: 3
GH: 8
Ammonia: 0 ppm
Nitrite: 0 ppm
Nitrate: 5 ppm

I don't think a 25% water change can make the KH drop so much, right? Should I be worried?

 

Have you checked your tap water to see what it is?

 

Have you checked your tap water to see what it is?

Well, just checked and tap water read as:

pH: 7.0
KH: 3
GH: 4

Not sure if 25% water change can cause that drop from 10 to 3 in KH even if the tap water is 3 KH.

What I understand with this drop in KH and a also a small drop in pH is that the water change plus a possible acidic spike that used up the Carbonate buffer to keep the pH stable (?)... My concern is that if there is something that need to be addressed to avoid pH further going down.

 

How long has the tank been set up?
With your source water results and if this is a newer tank, I’m more inclined to think there was something in the tank that increased the GH and KH and is now gone so that your water changes are bringing the tank back to the same parameters as your source water.
BTW, I’m very jealous of your source water. So perfect for soft water fish!

 

How long has the tank been set up?
With your source water results and if this is a newer tank, I’m more inclined to think there was something in the tank that increased the GH and KH and is now gone so that your water changes are bringing the tank back to the same parameters as your source water.
BTW, I’m very jealous of your source water. So perfect for soft water fish!

Only around 3 months. I started on march.

I think what increased my pH, KH and GH was the hardscape (Seiryu stones, lava rock and white sand), but I didn't think it would go down.

It makes sense that maybe is just how my tank water is supposed to be since the source is like that. I was kind of afraid since I read that the lower the KH, the less buffer I have in pH sudden changes.

About my water source, I suppose that is one of the perks of living in a underdeveloped tropical country. You can drink water directly from the faucet.

 

I personally wouldn't worry about it too much unless it is affecting the fish in a negative manner.

 

Only around 3 months. I started on march.

I think what increased my pH, KH and GH was the hardscape (Seiryu stones, lava rock and white sand), but I didn't think it would go down.

It makes sense that maybe is just how my tank water is supposed to be since the source is like that. I was kind of afraid since I read that the lower the KH, the less buffer I have in pH sudden changes.

About my water source, I suppose that is one of the perks of living in a underdeveloped tropical country. You can drink water directly from the faucet.

I’ve never used seiyru stone but I have read that it can raise ph. The sand can also, depending on what kind it is. Lava Rick is supposed to be inert.
Did you change much water as the tank cycled? If not, then the minerals accumulated and then decreased with water changes.
So it’s possible that it may still increase GH and KH.
I would do two smaller water changes twice a week versus one large one to try to avoid large swings in your hardness and of course, monitor as much as you can.
I run my tanks on RO/DI that I remineralize. My well water is not suitable. To keep the ph down for my lower ph loving fish, I make the water with a KH of 2. My tanks can go 2 weeks with just a slight ph drop. And I only do that when I’m away.
Good luck with your tank and let us know how it is going.
Just curious, what is your current stocking?

 

I’ve never used seiyru stone but I have read that it can raise ph. The sand can also, depending on what kind it is. Lava Rick is supposed to be inert.
Did you change much water as the tank cycled? If not, then the minerals accumulated and then decreased with water changes.
So it’s possible that it may still increase GH and KH.
I would do two smaller water changes twice a week versus one large one to try to avoid large swings in your hardness and of course, monitor as much as you can.
I run my tanks on RO/DI that I remineralize. My well water is not suitable. To keep the ph down for my lower ph loving fish, I make the water with a KH of 2. My tanks can go 2 weeks with just a slight ph drop. And I only do that when I’m away.
Good luck with your tank and let us know how it is going.
Just curious, what is your current stocking?

A mix of tropical fishes, but I think they're from different water parameters.

Angelfishes, Gouramis, rasboras, white clouds, swordtails, platies, pleco and ghost shrimps.

 

I think what increased my pH, KH and GH was the hardscape (Seiryu stones, lava rock and white sand), but I didn't think it would go down.

That's definitely the explanation, though only the Seiryu changes waterchemistry, Lava rock is usually inert, as is sand (except coral sand). But still then the readings shouldn't go down within a week with only 25% waterchanges. Might have done a bigger waterchange than 25% while changing the scape?

It makes sense that maybe is just how my tank water is supposed to be since the source is like that. I was kind of afraid since I read that the lower the KH, the less buffer I have in pH sudden changes.

Sudden pH-changes can only happen under certain circumstances and even at a KH of zero when the water is acidic enough pH is stable. It is rather hard to keep pH stable around neutral with low KH, but the infamous pH-crash is a myth.

A mix of tropical fishes, but I think they're from different water parameters.

Angelfishes, Gouramis, rasboras, white clouds, swordtails, platies, pleco and ghost shrimps.

Very much correct. Just going by water requirements the white clouds should be kept cooler (20-24°C) than the rest and swordtails and platies need hard water (GH > 10° and pH > 7.5). The others can go down as much as a pH of 5.5, with KH and GH at 0, which equals pretty much their natural habitat's parameters.

 

When I get a surprising test result, I retest.