Problems with pH/KH/GH

[AceReject]

Good evening,

I’m hoping someone might be able to help me with my pH/KH/GH problems.

I have a 160L tank and the current occupants are: 10 cherry barb, 6 albino cories and 1 BN pleco. There’s also a few cherry / armano shrimp which are new additions.

The tap water in my area is ridiculously soft. Both KH and GH read at zero when I first got the tank. The pH was very slightly acidic. My two LFSs have both confirmed that this is normal for our area.

So every day I am doing the NT Lab aquarium tests and dutifully recording the results. I’ve tried to up the KH and GH using a range of methods. I’ve added a lump of some rock recommended to me by my LFS, I’ve added crushed oyster shells and I’ve been using some KH & GH Up products. I’m currently up to the dizzying heights of KH = 4 and GH = 9. The problem is that the KH Up products seem to keep raising the pH too. It started around 6.5 during my fishless cycle but eventually got up to 8. With the help of a bit of pH Down, it’s currently fairly stable at 7.5 since the fish were added.

So my dilemma is what to do moving forward? It seems impossible to get the KH up to advisable levels without skyrocketing my pH. Is this correct? I thought the whole point of the KH was to stabilise and buffer against pH fluctuations, but if trying to get it to an advisable level means sacrificing my pH, it seems like a completely pointless exercise? Does anyone have any suggestions for me moving forward? I don’t really want to keep chucking Up and Down products in.

The second part of my question regards changing my pH from its current 7.5. I have my heart set on some green neon tetras, but I’m told they need 5.5-6.5 pH. If I very slowly start lowering my pH to 6.5, will the current occupants be ok with this? Or am I now pretty much stuck with the 7.5 they have now?

Thanks for taking the time to read this, and I look forward to any suggestions.

 

[Aiken Drum]

KH is carbonate hardness. Thats carbonates and bicarbonates disolved in the solution. Adding carbonates and bicarbonates will raise pH. That's just how it works.

KH or buffering capacity will absorb acid and prevent the acid from causing pH swings. So it will keep it closer to the higher pH you arrived at by increasing the KH. It wont keep it at the lower pH you had before increasing the KH.

Fish are very adaptable. Trying to attain a steady pH is more important than trying to reach an ideal pH.

My recommendation would be to let your pH and KH just settle where it settles and dont try to chemically alter it. Keep water chemistry stable by regular water changes. The rock and crushed oyster you added will add some buffering from pH swings should you need it, but you dont know if you needed that buffering capacity or whether your pH would have held steady just with water changes.

 

[AceReject]

Thanks Aiken. That’s makes sense. I do really appreciate you taking the time to answer.

 

[Aiken Drum]

Water hardness, pH, alkalinity etc and how changes in one can effect the others is some pretty complex water chemistry, and i certainly dont fully understand it. In the normal course of things its not something you need to consider. Dont overstock and keep up with water changes and most of the time you will be good.

With very soft water those rocks suggested by your LFS (limestone?) and crushed oyster shells can provide a steady supply of carbonate hardness to prevent those pH swings you are trying to avoid.

 

[AceReject]

Thank you. Yes, I think it’s limestone although I’m not really certain tbh. It looks a bit like a creamy white skull, so I’ve shoved it behind some plants. Halloween wasn’t really the look I was going for in the tank.

Thanks again for the help. Much appreciated.