Do all PH raising rocks eventually result in the same PH levels?

[Watermania]

I have bought 2 types of rock recently, both sold as not effecting PH. Unfortunately both have increased the PH.

The rocks standing upright have changed PH from 6.0 to 7.8 over hours and the rock lying across them has changed the PH to 6.8.
As I’m wanting to add some German Blue Rams 7.8 is too high but the 6.8 is ok.
My concern is whether the rocks changing the PH to 6.8 are just slowly effecting the PH and will eventually lead to high PH as well or is it likely to stabilise at 6.8?

Do all rocks that effect PH eventually result in the same PH levels or can different rocks level out at different levels?

 

[Sunnyspots]

I had a question about a rock before and was recommended to test it out in a separate tank before trying it with fish so that I would know what it changes, if anything. Perhaps you should try that over a few weeks, ideally testing each type of rock separate from the others.
PS nice rocks!

 

[Freddo96]

It's Highley likely it will stabilise at 6.8 with weekly water changes I would leave it 7 days check it again and do a water change then add fish

 

[Byron]

It is not necessarily the rock raising the pH, so we need to know a couple of things. First, did the store havee any name for the rock? I'm not a lapidary expert, but I would guess this may be basalt.

Second, the extent to which calcareous substances may affect the parameters depends upon the initial GH/KH/pH of the source water, and the substance including the volume. I have never heard of any calcareous rock/gravel/sand "wearing out" over time.

When testing pH of tap water you need to ensure any CO2 is out-gassed as this will affect the result. Does not apply to aquarium water tests. My thought here is whether 6.0 is the fresh tap water pH or the aquarium water.

 

[Watermania]

The water measuring 6.0ph is taken from another fish tank. I then siphon the water into a buckets that has an air stone in it.
The bucket of water is filled so it only just covers the rocks.
I don’t know what the rocks are as they weren’t labelled. The LFS did tell me a name but it was unfamiliar and I don’t remember it.

I don’t have a few weeks to test as I only have a week to return them, which is why I’m asking here. The 6.8ph rock would be fine unless it too carried on over the next few weeks to 7.8ph.
Sorry I don’t know the hardness of the water.

The rock in the photo is the one currently showing 6.8ph.

 

[Colin_T]

The only rocks that change pH are limestone and sandstone. These are made from calcium and are white in colour. The rocks in the picture are not limestone or sandstone and should not affect the pH.

If you want to test the rocks for calcium, take the rock out and dry it. Then put some vinegar on the rock. If it fizzes and foams up, the rock is calcium based. If it doesn't fizz or bubble, the rock is not calcium and will not change the pH.

------------------
As Byron mentioned, the pH can change after the water is allowed to sit for 24+ hours. When tap water is under pressure (like in the water pipes), the dissolved gasses in the water can be forced out and if the oxygen is removed, then there will be more carbon dioxide in the water, and this can drop he pH. When the water is allowed to stand for 24 hours, the dissolved gasses get back to normal levels and the pH can change.

To test the rocks in water, set up 3 or 4 containers of water. Leave one container of water without any rocks in, and put rocks in the other containers. Monitor the pH before adding rocks and again 24 and 48 hours later, and then a week after that. The bucket with water only is the control bucket and that tells you what the pH of the water should be in the other buckets. If the water with rocks has a different pH, then the rocks are affecting the pH.

 

[Avel1896]

Hey
It depends on their calcium content/percentage. What's its name ? Seeing white lines I'm pretty sure it is limestone.

 

[Watermania]

I had a tank without fish in when I bought the rocks. The reading was 6.0ph. I put the rocks in and 2 days later I saw a reading of 7.2ph. Therefore the rocks are definitely effecting the ph.
It is then that I got extra buckets out and took water from another tank, also 6.0ph and placed the rocks in the bucket. One type of rock has taken the ph to 7.8. The other type of rock took it to 6.8ph. To me it’s pretty clear that the rocks are increasing the ph
I have until Wednesday to return the rocks so don’t really have time to experiment much longer. Whatever the rocks are they are effecting the ph but to what extent I don’t know…hence the thread and opening question.

 

[Byron]

If you intend soft or very soft water species (rams were mentioned), a pH of 6 would be ideal and you don't want pH-affecting substances in the tank.

 

[Avel1896]

Some rocks are chalky other aren't. What's rock name ?

 

[Watermania]

I have put vinegar on it and can see lots of small bubbles rising. It’s not exactly foaming but it is reacting. Ive tried taking a photo but it’s not easy to see.

 

[Byron]

I have put vinegar on it and can see lots of small bubbles rising. It’s not exactly foaming but it is reacting. Ive tried taking a photo but it’s not easy to see.

That pretty much confirms it is the rock, so at least you now know.

 

[Avel1896]

Vinegar isn't the best way to check chalky stone. Use hydrochloric acid.
If "vinegared" rock shows lots of bubbles hat means your rock is very chalky because vinegar is less effective than hydrochloric acid.
You will never be able to lower or stabilise pH as long as this rock is in the tank.

 

[Watermania]

Yeah, it’s going back. Disappointed they sold it as not ph effecting.
I don’t have hydrochloride acid but I did have vinegar so just used that.

I’ve also put water into an bucket without rock into it. Surprisingly it has increased PH by the same amount the other rock has increased to around 6.8ph. From this I’m going to presume that the other rock won’t change the ph.

 

[Colin_T]

Vinegar is safer than hydrochloric acid and has a similar pH (around 3.0). It is all I use to test rocks and has been used for years with good success. it's also cheaper and easier to get than HCl.