Help Kh and gh rising, why??

[shandellrae]

Hello again.

I am in the process of switching my 65 gallon from tap to RO. Doing 25% WC every 2-4 days. Starting kh was 25, gh was 0-1. As of November 4th, the kh was 7 and gh was 5. I was going to the first big water change today so I tested before just for shits. Kh is now 11 and gh is 6. What could be causing them to rise? The only new thing I've added to the tank since the 4th is a bunch of snails. I will add a photo of the fertilizer I use. Ive been adding it after water changes. I dont have any rocks. Play sand on top of aquasoil, a big acacia stump. This wasn't happening between all the other WC I've done so I'm just confused lol

Forgot to add... I tested the water straight from the ro unit and numbers are 0. And I also just tested the water after it's been remineralized with equilibrium and sitting in a bucket for a few days. Kh is 2. I didn't think equilibrium raised kh? Or it something leaching from the bucket??

 

[SingAlongWithTsing]

some sands can raise kh too. i would test some play sand in a bucket of ro to check.

 

[Unexpected]

Equilibrium definitely doesn't raise KH. It raises GH, K and Fe. Keep that in mind. Also, water by nature creates its own KH, but so slightly you wouldn't be able to test it with our hobby kits. It's most likely the sand if you have no rocks or ornaments. Take testing with a grain of salt. We make mistakes in general and these kits are just hobby level. Just keep making RO and try to get GH to six or seven and don't add any KH unless you have fish like African Ciclids or Endlers. I would add the Equilibrium to your RO storage to what you want and start doing daily 25 or 50 percent water changes until the tank water starts to match your dosed RO water. Then just monitor from there.

If you want to ask more questions, just hit us up here.

 

[rzn7z7]

I'm guessing the kH rose due to carbonate buffering...the RO water sitting in the bucket absorbed some CO2 from the air which, due to carbonate buffering, leads to the formation of carbonates until an equilibrium is reached

A couple of YT videos explain it better than I can

 

[Koan]

kH rose due to carbonate buffering

KH is carbonate buffering, it's the presence of carbonate ions in water that disassociate from dissolved mineral carbonates like calcium carbonate CaCO3, or potassium carbonate K2CO3, or sodium bicarbonate NaHCO3.

The minerals have to come from somewhere

 

[PeerUnk]

KH is carbonate buffering, it's the presence of carbonate ions in water that disassociate from dissolved mineral carbonates like calcium carbonate CaCO3, or potassium carbonate K2CO3, or sodium bicarbonate NaHCO3.

The minerals have to come from somewhere

On another forum an expert mention in fact, the pH determines whether KH gets formed. For instance when you add a strong base (not advised, just for explaining purposes) not containing carbonates, like NaOH (sodium hydroxide) indirectly increases KH by converting CO₂ and hydroxide into bicarbonate/carbonate.

So adding any base (OH-) ends up being (bi)carbonates (KH increases).
Just like the opposite:
Adding an acid (H+) eliminates (bi)carbonates (KH decreases)

For those who are interested in the pH buffering topic: Phosphates buffer the pH as well. In very low KH environments this is a factor to be aware of.

The minerals have to come from somewhere

Very true. Most probably from the play sand like suggested.