pH different in every tank....odd?

[Fishyfanatic]

On Sunday I broke out the master test kit and spent about an hour testing the water in all our tanks (shaking the Nitrate vile for 5 different tanks got SO tiring). Anyways, I noticed that the pH is different in every tank. I can understand the 150 because we use crushed coral. Here's the numbers:
10 gal = 6.0
QT = 7.6
29 gal = 7.4
5 gal = 7.2

They were distinctly different in colors. I tested the pH in all of the tanks and put them side by side and they are all different. What is causing this?

We don't use any chemicals except for dechlor and it doesn't alter the pH. The 10 gal REALLY shocks me to be that low. None of the tanks have driftwood or any rocks except for ones that are fake (ceramic or plastic) except for gravel in the 10 and 5.

 

[jsoong]

You should check the KH in all the tank .... may be you are exhausting the supply of buffers in the water, so the pH drops.

Is anyone dead in the 10 gal? (maybe a snail) ... decomposing stuff creats acids & can overwhelm your buffers in a hurry.

 

[TankGirl]

Definitely check KH and other suggestions from jsoong.

Also, is the 10gal the oldest tank? Over time acidification occurs from decomposing matter and lowers the pH, and in a small tank like that you're likely to see a drop. I'd be interested in if the pH shifts following a water change, and if it does how long before it reverts back. What is the pH of your aged tap water?

 

[Fishyfanatic]

The 10 gal is the oldest tank. But a couple months ago I tore it down and started over from scratch. I won't be back to my apt until Saturday night but I will see if James can test the KH for me.

AFAIK there aren't any dead fish or snails in the 10 gal. If I see a snail that doesn't move for about a day I always take him out and put him in the QT with the lights out (completly dark) and check back about an hour later. If he has moved then I know he's still alive. If not, I get rid of him.

When I test the pH about a day later it's about 7.6. I can understand it varying by about .2 to .4 but not by 1.6.

 

[BrianNY]

This is not unusual in water that has no buffering capacity. My tap water contains no KH, but is rich in CO2. As the CO2 gasses out, the pH rises. Then the normal biological processes in the tank drastically reduce the ph.

The likelihood is the pH in the 10g is way under 6. That's the lowest reading on a reagent test kit. I've tested with a digital test meter and found that the pH was actually 4.4 when the color test read 6.

Read the article on pH stability. It will explain all of this in detail.

 

[Fishyfanatic]

Do I need to add something to my tank to raise the pH then? I don't have the option of putting anything in the filtration unit since it's a small hob. Maybe a piece of limestone in the tank?

 

[BrianNY]

A handful of crushed coral will gradually raise your KH thereby stabilizing your pH.

I use a mesh bag full placed in the HOB.

 

[TankGirl]

Anything calciferous will help, including adding crushed coral substrate or a limestone rock or shell decoration, but you could try fitting some into your filter as BrianNY suggests.

If you can't fit some in there, Duetto and Fluval make some nice internal filters that you could fit into the tank, which are cheap and you can put only CC in them, and they run on an air pump.

 

[Fishyfanatic]

Here's the hardness results in the tanks:

QT = 53.7
29 = 107.4
10 = 17.9
150 = 71.6

Does that seem odd that they vary by so much? Obviously the hardness in the 10 is VERY low. I just bought the filter for the 10 a couple months ago and I hate to replace it already so I am thinking that I'll get some limestone pieces and form something in the tank. The tank is pretty bare of decor right now. I kept it that way because I love watching my snails. I don't even have a peice of greenery in there. I don't recall the brand of filter that it is but it has an activated carbon cartridge and a black foamyflossy thing. I don't know exactly what it is called.

It also strikes me as being odd that the hardness in the 150 is that low, considering that the pH is very stable at 7.6 and we have two bags of crushed coral in the filtration unit. And then the hardness in the 29 is that high and I don't have anything in the filter except for the cartridge.

 

[jsoong]

What is the KH of your tap water & how often are you doing pwc's? If your tap has half decent KH, you can replenish your buffers just with water change.

I think adding some calciferous material to the 10 is a good idea. I don't have snails, but have read that they need a good source of CaCO3 to build their shells, and that is obviously lacking in water with such a low KH.

This may be totally off the wall .... could the snails be taking up the CaCO3 from the water at high enough rate to affect the water parameters? .... any snail keepers out there know the answer?

 

[Fishyfanatic]

I was doing 20% water changes about every 3 weeks but for the past couple weeks I've been doing 20% weekly. The Nitrates were getting out of control and I need to do water changes weekly, or whenever they get to 40, whichever comes first.

Maybe the snails ARE sucking up the calcium. That's one theory to it. I guess adding limestone can't HURT the tank. I mean, the pH is already so low. I'm not exactly sure what the KH is out of the tap. That's something that I will have to test tomorrow night. But I think that on my way home tomorrow I will pick up some limestone pieces.

 

[TankGirl]

I have snails in most of my tanks and all I can say is that without adequate water hardness their shells begin to turn white, thin out and become very weak. They definitely benefit from either food with a calcium source (I know someone who bakes up "cookies" for her snails that include egg shells, minerals, veggies and whatnot!) or decent water hardness. I would imagine you would have to have a sizable snail population for them to actually deplete the measurable hardness (we are talking GH here, right?) in the tank, but maybe it is possible in a 10gal.

You do ask the hard questions, jsoong!

 

[Fishyfanatic]

Actually TG, I was talking about KH. I didn't test GH. I guess I need to test those tonight then?

 

[TankGirl]

General hardness, or GH is a measurement of the dissolved concentration of magnesium and calcium ions, so that is what you mean when you refer to "hard" or "soft" water. KH (buffering capacity) measures the water's ability to keep the pH stable as acids or bases are added (like CO2 being an acid will drive down pH without adequate buffering) and I like to call it alkalinity. So technically you could have soft water with a high KH.

KH and pH are really intertwined so whenever you notice a change in pH, or you are going to add something in your tank that might alter pH, you want to measure KH. If a fish profile indicates a fish requires "hard water" they are referring to GH, not KH - fish don't care much about KH itself, AFAIK.

Jsoong, set me straight if I have something mixed up -

 

[Steven A]

Cant some p.h's change according to stuff / decor or substrate in the tank ?
i.e. bogwood toxins lowers the p.h.
Is this true ?

 

[TankGirl]

Cant some p.h's change according to stuff / decor or substrate in the tank ?
i.e. bogwood toxins lowers the p.h.
Is this true ?

Right. Those things, decor like driftwood, rocks and substrate, release acids (driftwood, peat) and bases (some rocks and substrates) into the water, raising or lowering the pH. How much they raise or lower it will depend on the alkalinity, which we measure with a KH kit.

 

[jsoong]

Bog wood releases tannic (& other) acids, so will lower pH. I don't think these acids are toxic tho .....

Any carbonate / bicarbonate substrate (eg limestone, shells, coral) will increase the KH & so the pH. There are lots of other things that will change the pH of water (esp. when the buffering capacity of the water is poor).

 

[Fishyfanatic]

I am going to test General Hardness and report back with levels.

 

[Fishyfanatic]

Ok, I have the GH results:

QT = 35.8
10 Gal = 35.8 (could be 17.9)
29 Gal = 71.6
150 Gal = 143.2
5 Gal = 53.7
Tap = 53.7
Aged Tap = 53.7

 

[Fishyfanatic]

Two of my ivory snails are on the verge of death. We were doing water changes and noticed that their shells had holes in them. It's odd because none of the others do. Something in that tank is making the pH go REALLY down and the hardness low. All that is in it is gravel, air stone, heater, ceramic mini castle, plastic rock, and filter.