Level Check

If you are growing healthy plants, then I will assume your CO2 levels are good.
Otherwise, I see no problems in your listed specs. Just wondering why you keep such a low Ph, or is it due to your Co2 levels?

If you are not injecting Co2 and are using low lights, then id leave well enough alone. In that case, your plants must be low light plants and are happy enough with what you are offering them.

If I remember correctly though, Co2 can be calculated by finding you KH and Ph and looking at a scale. I had a test kit once that had the scale, but Im sure others who know more about plants than I do could help you out more on the gardening.

And yes, a stable Ph is MUCH better than a perfect one. If your fish are happy and healthy, DON'T mess with it.

I wasn't commenting negatively on your Ph level, just kind of struck me as odd to be so low.
But by all means, don't mess with it. Just keep it in mind if you start to tinker with the idea of keeping fish who prefer a much higher Ph.

You don't really need a CO2 test kit, as you can find the amount of CO2 you have in your aquarium via the kH and also the pH of your water.

http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm

There's a link to Chuck's calculator, there's even a version that you can download and play with

Thank you Dark. I knew there had to be a calculator or scale out there somewhere in case he was curious.

Your pH is low because your KH is low. Low enough that you'd want to keep an eye on it.

3 dKH is normally given as the safe low. A little bit of crushed coral in the filter can help bring that up. Regular water changes can help replenish the buffer… I wouldn't let it slide for too long. Its low enough that you should be aware of it.

As stated a stable pH is the best thing. And with tetras in the tank they prefer the softer water anyway. Good water changes weekly will help kepe the pH stable. My pH is around 7.4 but my water is softer than yours. As long as I do minimu 20% water changes ( I aim for higher) each week then my pH doesn't go lower. Loesser water changes over a period of a month drop my pH fairly low.