Will most rocks have no effect upon pH?

[Ellie11]

I’m in the process of lowering my pH for P.altum, the big angelfish. Would slate affect the pH? I used it without concern in other tanks, but these are sensitive fish. While researching pH reduction I came across a 2010 post by written I think by Bryon here. Brilliant! I have been getting conflicting ”facts” for days & as soon as I saw what def appears to be the Bryon here’s post, I knew I had the truth and only the truth

 

[BettaFishGirl]

I've never heard of slate affecting pH. I think it is safe to use, but I'm sure others will confirm that.

 

[Ellie11]

I've never heard of slate affecting pH. I think it is safe to use, but I'm sure others will confirm that.

Thanks, Same here, just double checking because these are high maintenance fish that require acidic water.

 

[Magnum Man]

The question "most rocks"... most rocks won't leach minerals into water ( at least faster than you are removing them with your normal water changes )...

softer rocks that contain calcite ( like limestone ) will leach into the water & can alter the Ph, albeit, depending on water change volume & frequency, may not change it much... harder stones like granite will make very little difference...

you mentioned slate... "Slate is composed mainly of clay minerals or micas, depending upon the degree of metamorphism to which it has been subjected. The original clay minerals in shale alter to micas with increasing levels of heat and pressure. Slate can also contain abundant quartz and small amounts of feldspar, calcite, pyrite, hematite, and other minerals"... it's basically like river bottom mud petrified into rock... I would think it would be pretty natural in an Altum tank

slate is not likely to alter your Ph, & it's components if leached into the water would likely push it down, rather than up, as would limestone

 

[WhistlingBadger]

Slate and clay stone don't usually affect pH as far as I know. They can leach silica into the water, which can lead to diatom blooms. Sandstone will do that too; it is generally inert but around here it can have a ton of iron in it, which can lead to algae blooms.

I usually choose rocks for my tank that are water-rounded. Around here, that means granite and other hard, metamorphic types, which are chemically inert. Limestone and its relatives don't turn into rounded river stones; they dissolve in water over time and become pitted and jagged.

 

[Ellie11]

The question "most rocks"... most rocks won't leach minerals into water ( at least faster than you are removing them with your normal water changes )...

softer rocks that contain calcite ( like limestone ) will leach into the water & can alter the Ph, albeit, depending on water change volume & frequency, may not change it much... harder stones like granite will make very little difference...

you mentioned slate... "Slate is composed mainly of clay minerals or micas, depending upon the degree of metamorphism to which it has been subjected. The original clay minerals in shale alter to micas with increasing levels of heat and pressure. Slate can also contain abundant quartz and small amounts of feldspar, calcite, pyrite, hematite, and other minerals"... it's basically like river bottom mud petrified into rock... I would think it would be pretty natural in an Altum tank

slate is not likely to alter your Ph, & it's components if leached into the water would likely push it down, rather than up, as would limestone

Thanks so much for this excellent post!

 

[Ellie11]

Slate and clay stone don't usually affect pH as far as I know. They can leach silica into the water, which can lead to diatom blooms. Sandstone will do that too; it is generally inert but around here it can have a ton of iron in it, which can lead to algae blooms.

I usually choose rocks for my tank that are water-rounded. Around here, that means granite and other hard, metamorphic types, which are chemically inert. Limestone and its relatives don't turn into rounded river stones; they dissolve in water over time and become pitted and jagged.

You mean round like river rocks? I have some of those. A bare bottom tank has been recommended, with lots of driftwood & those almost tea leaves.
I am finding it too stark & wanted to use some flat slate to soften the look

 

[PygmyPepperJulli]

I've been putting vinegar on rocks collected from creek to see if they start fizzing to check if they are alkaline... I've never actually seen one that does though, so now I'm doubting that this actually works and am now worried about my pH... Opinions? I still desanitize them before I put them in, but I don't want to alter my tanks pH (I have soft and acidic water fish in there).

Thanks.

 

[Ellie11]

Yes, I read about the vinegar test too. Never tried it. I am pretty much convinced most rocks are chemically inert except for limestone & similar rocks. That‘s sure what my research indicates

 

[GaryE]

The vinegar test never worked here.

We all live on different geology, so what's usual where I am might be rare where you are. I've used a lot of slate and am experimenting with using a locally common shale. The jury's out on it, but it is ideal for building structures.

I had trouble with sandstone, and limestone is as bad as they say. I use a field guide - I find it more practical than online sources - and first look up what I think I have. Unfortunately for softwater lovers, there are a lot of rocks that release minerals. It's more than limestone.

Once I eyeball the rocks with the guide, I realize I know nothing. It isn't easy. So I use my trusty tds meter after putting them in water, to see if the chemistry changes over a couple of weeks. That's with rocks I'm not sure of.

I find a lot of basalt and granite on beaches here, so that's no question. It's the sedimentary rocks that that I question. They don't answer so I have to test.

 

[Ellie11]

So you’re saying basalt & granite are inert? I will check around. Any idea if pet shops commonly stock them? This altum expert in Germany swears by basalt. He has a biotrope unlike anything i ever saw. like he brought a ColumbIan river home & shoved it in his tank. He didn’t know about slate for sure.

 

[GaryE]

Basalt has been great. I just walk across the street and pick it up, give it a rinse and use it. But because my source is a beach, it's rounded. Granite is very stable, but red granites seem to ruin fish photos. Around here, the best sources are highway cut throughs where hills have been dynamited to create road passages. You get good granite chunks there.
I've never bought a rock for a tank - but I am preparing some softwater rapids tanks, so I've been going for a lot of walks with a shoulder bag on.

 

[Magnum Man]

I think the vinegar will only show you rocks that may raise your Ph… as vinegar is an acid, it will do little to show anything to rocks that are acidic, or to harder rocks like granite, also, I did a little digging, and granite can actually lower your Ph, so it would not react to vinegar… but while Granite “could” lower your Ph, it’s minerals are locked up tightly, so it goes back to my 1st post, most rocks won’t leach minerals into you tank, faster than you are removing them with your normal water changes

You could do an experiment, by placing rocks you are considering adding to your tank, into a jar of water, and do Ph tests on it daily / weekly… you’ll have to cover the jar, as evaporation will effect your results… this would really only show you the stability of the rocks, aeration and water movement in your aquarium will give faster changes, but they should mirror the direction the Ph went with jar experiment…

 

[Essjay]

You could do an experiment, by placing rocks you are considering adding to your tank, into a jar of water, and do Ph tests on it daily / weekly… you’ll have to cover the jar, as evaporation will effect your results… this would really only show you the stability of the rocks, aeration and water movement in your aquarium will give faster changes, but they should mirror the direction the Ph went with jar experiment…

And set up another jar with just water, treated the same way as the jar with the rock and test that at the same time as the jar with the rock. If the two are the same, the rock is inert; if they are different the difference is due to the rock.

 

[emeraldking]

I wouldn't use the word "most" in this case. For there are also rocks in nature that do affect the pH. But for sure not all... It really depends on the type of rock we're dealing with. "But" most rocks sold at an lfs won't affect the pH.