local rocks and ph .. trouble reading test

djrodan

I recently added some local rocks to my tank, hand picked off the top of our local mountain range in the Hudson Valley, the Shawangunk Mountains. The type of rock is a quartz conglomerate. Ive made some awesome caves with them and I'm very excited with the new addition to the tank. Of course I was very weary with using them as I really don't want to mess with my tank parameters, its a new tank probably 4 weeks into the cycle.
I asked my geologist friend if they might alter my ph. He said its mostly quartz and has very little carbonate in it, so it shouldn't. He also added that the water from my tap is run off from these exact rocks so the ph should match. I've been testing my ph daily to watch for changes from the rock but I've recently realized that the test kit is hard to read.

I'm using the liquid API kit.
My tap water is already high, Around 7.4 (on the regular ph test the color turns out to be blue with a slight tint of green).
My tank water is a clear blue on the regular ph test. (7.6+)

On the high ph test:
The tap water is a light brown, im guessing between 7.4 and 7.8.
The tank water is a darker brown than the tap, but its hard to tell exactly how brown, but has NO purple-ish tint. Its stayed consistent for the past 3 days, and I'm still monitoring. Somewhere around 8.0

The high range test is the only test where the color gradient isnt a smooth gradient, which is throwing me off.

My questions are:
Could an addition of rocks like this increase the ph to a point then level off?
What do you think of my ph currently, is it too high, and should I lower it, or will the effort to lower it be lost if I decide to keep these rocks in there? (I understand this depends what types of fish I want to stock. answer: general community fish)
Any comments on the API ph test kit?

Byron

On the basic pH test, is the blue at the upper end of the range on that test? If yes, the pH may well be higher than that test goes. If the high test shows the same pH for the tap water as the basic, which is what you are indicating, then the "high" test is likely going to be more accurate in this case.

It could be the rocks, or something in them. I would agree that quartz is normally inert, but it may contain any number of other minerals or bicarbonates that might be calcareous [which dissolves calcium or magnesium into the water, raising hardness and corresponding pH]. There is also the substrate, gravel or sand which may be calcareous.

One test is to dry the rock and drop a couple drops of acid and if it fizzes the rock is calcareous. Same test works for the substrate. Some use vinegar, but it is quite a weak acid. If you have the API nitrate test kit, the Regent #2 is acidic and will work. Just a couple drops.

The pH is connected to the hardness, and should you decide to alter the pH it will be next to impossible without changing the hardness of the water. You can read more of this connection here:
http://www.tropicalfishkeeping.com/f...quarium-73276/

General community fish covers a lot of variables. Livebearers and other hard-water fish will do fine in your water as is. Many "basic" fish will manage too. Some soft water species, and any wild-caught soft water fish, will not. The water parameter section in our fish profiles sets out suitable parameters for each species.

Byron.

djrodan

My LFS tested my hardness today and said that my water isnt hard at all.

The Nitrate reagent #2 produces no bubbles on the rocks.

My substrate is simple shale.

I'm going to do some regular water changes and substitute my tap water for bottles water from the grocery store. I'll try and lower it slightly, but not go crazy. I was only panicking because I thought it was nearing 8.0.

Are the basic 'Aquafina, Poland Spring, Dasani... etc" fine for this? As long as the water is spring water and not distilled?

Thanks Byron!

Byron

I've no idea what may be in the bottled water, in the way of minerals. The rocks and shale sound OK.

Until we know the numbers for the tap water hardness, we would only be guessing at attempts to lower the pH. The LFS should give you numbers; "not hard" means nothing really, as that article should demonstrate.