tap water vs. tank water test results

[gale]

Ok I tested our water in the bathroom tap (which goes thru the softener) and the kitchen cold tap (which does not go thru the softener) and tank water. Here are some results:

tank water ph 8.8 (maybe higher, but that is as high as the test goes)
both taps ph 7.6

So WHY is the ph raising in the tanks? It's doing it in both tanks. My 20g has a ceramic type cave, plastic air dinosaur, and regular aquarium gravel, plus a few plants. My 10g has a rubbery plastic flower, a ceramic looking decoration and a ceramic no fishing sign, plus a couple of plants, plus driftwood, and regular aquarium gravel. Both have HOB filters. The 20g is aerated additionally via the dinosaur and the 10g is not aerated additionally. Any ideas?

Ok now hardness-I only have test strips for this:
bathroom tap is very soft (0-25)
kitchen tap is very hard (over 150)

Alkalinity (says ability to buffer or something like that)
all water registers 300 on the test strip, which is the highest it goes.

Other parameters are ok but strangely the 10 gallon tank is usually zero-5 nitrates and the 20 gallon tank is usually 20-30 nitrates, even though it has more than twice as many plants.

We've been using only soft water in the tanks but have decided to use a mixture of hard and soft since the snails and shrimp could use the extra hardness I guess. We'll do it slowly over the next couple of months so the fish can acclimate gradually.

But the ph being so much higher in the tanks has me completely puzzled.

 

[air*force*one]

i only read the first little bit im in a rush but do you have shells in your tank cuz that will boost the ph right up same with oyster chells that you can buy in bulk. if you want to bring it down use p.h down it wooks awsome .

 

[gale]

AFAIK there is nothing in my tank that would raise the ph. I don't want to add any chemicals to it and my fish are acclimated to the ph in the tank. I'm just really curious what would make it go up from the tap water that way.

The only thing I'll probably alter is the hardness by using a mix of hard and soft water. Just need to work out how much and how to get the temp close.

 

[Phantom Thief]

It has to be something in the tank. It could be the gravel, something in the filter, anything! I would recommend you took a little of everything, put them in seperate containers with tap water, and then see if any of the items cause a pH change.

P.T.

edit: forgot to add that another thing you might want to do is to fill a bucket with tap water and leave it for a few nights and then check it. It may be that some dissolved gas or some other thing is the one causing the pH to be low when it comes out from the tap, so once the gas has dissipated, the pH level goes up.

 

[gale]

forgot to add that another thing you might want to do is to fill a bucket with tap water and leave it for a few nights and then check it. It may be that some dissolved gas or some other thing is the one causing the pH to be low when it comes out from the tap, so once the gas has dissipated, the pH level goes up.

Oh good point-I hadn't even thought of that. I do know this-our water is well water so it isn't chorinated (but I still use dechlor). When we first get it from the sink (the cold unsoftened water) it tastes gross but about 24 hours later it tastes less gross if that makes sense. I don't drink it but my husband does.