Question on PH

Have a question on ph for you guys

Ph of tap water straight from tap - 6.8 -7.0
Ph of tap water after sitting for 24 hrs in cup - 6.6 - 6.8
Ph of aquarium with 2 big 1 kg - 2 kg lumps of sea rock 7.0 - 7.2

In my previous aquarium I had a problem cycling it due to low ph (under 6 and was lower than the scale of my test kit) which I was putting down to my tap water being very low. ( had not wood etc in old tank to lower it) so would my true reading of tap ph be after 24hrs? If it is I might as well remove the sea rock.

 

While there may be other reasons, one reason your tap water ph goes down after sitting is that it absorbs COs which will slightly reduce ph. I would call the true ph whatever it is when you add it to the tank. Most let it age for a day or two before adding it so that would be yours.

 

While there may be other reasons, one reason your tap water ph goes down after sitting is that it absorbs COs which will slightly reduce ph. I would call the true ph whatever it is when you add it to the tank. Most let it age for a day or two before adding it so that would be yours.

So the aged 24hr then, that’s strange how my ph dropped below 6 in the past.

 

Why would you remove the sea rock? Your true pH is after sitting out for 24 hrs at 6.6. That's playing with fire bc your KH is most likely very very low to non-existent. You want to have a KH of 4 (recommended) to keep your pH stable. Without knowing KH, I can't tell you for sure, but since your tank pH crashed already, i'm almost positive it is very low. Imo and ime, I would keep buffering water to 7.2 at least. That value is totally fine for soft water fish.

It really helps to see the big picture if you can test KH and GH though, so if you can get a test for yourself or KH/GH tested on tap and tank, that would be great

 

Very good point, I will have to test those parameters just to see what they are. Can’t remember if I have those test kits. Its not the end of the world leaving the sea rock in my tank it was just more of me being confused about it not being as low as I expected. Will report back my tests to see what’s going on.

 

So pH is not as low as you expected because the sea rock is buffering KH. The higher the KH, the more stable pH will be and it will take a lot more to reduce pH with a high KH. When KH is low, it (usually) lacks alkaline minerals and it doesn't take much to start dropping. The lower the pH, the faster it will drop too!

 

So pH is not as low as you expected because the sea rock is buffering KH. The higher the KH, the more stable pH will be and it will take a lot more to reduce pH with a high KH. When KH is low, it (usually) lacks alkaline minerals and it doesn't take much to start dropping. The lower the pH, the faster it will drop too!

I was meaning not as low out of the tap I just expected it to be 6. So I found a kit for kh & gh and test is as follows

Tap kh 1-2 drops - 0-50ppm
Tap gh 2-3 drops - 0-50ppm

Tank kh 3-4 drops - 50-100ppm
Tank gh 7-8 drops -100-200ppm

So you were right

 

So you expected tap to be 6 pH? That would be very unlikely. I wouldn't consider that healthy enough to be stable pH.

Ok so your tap water is very soft. Exact same KH/GH as mine, it's how I had to learn about all this in the first place.

Anyway, you can keep the sea rock. It's doing well to keep KH buffered. The only other way to keep KH high enough so pH doesn't plummet is to change out (say 50%) water every week. Still that would only keep KH at 1 or 2. So the extra buffering is helpful for you. The tank params are very good imo. What type fish are you keeping?

 

So I will be Keeping the sea rock in my new tank for sure too because it’s really not worth the hassle of removing the rock as everything’s going well and is stable as you said.

I already have a strict 50% weekly w/c so that’s not an issue with doing that. The fish I’m keeping are ok at my range, tetras, honey gourami and ottos and are doing well.