Originally Posted by npjpkac
So you think I'm better of just leaving my DPs where they are at?
Not necessarily. There are two important points. First, avoid fluctuating water parameters; short-term, any fish will be less stressed and therefore healthier if the water parameters are steady. However, long-term a fish should be maintained in water having parameters that it "prefers" due to its natural habitat.
I am not familiar with the several species of puffer fish, and just searching a bit now I came across quite a few with differing needs. I suggest you research the species you have, find out their preferred water parameters, and then work to establish those in your aquarium. I would assume you have your puffers in their own tank, which is what you list under your signature, so that is good. A 10g is easy to adjust if that is necessary.
Some of the species I found online do well in soft, slightly basic (alkaline) water, and some species are better suited to brackish water, which would obviously be a bit harder. Your water is probably soft, so raising the pH with dolomite, crushed coral or marble chips will be straightforward. Adding any of these rock substances (in gravel or crushed form) either mixed in the substrate or in the filter will work. Do it slowly; it does not take much to raise the ph and sudden fluctuations are stressful. Going from 6.2 to 7.2 for example should be done over a couple of weeks, no more than .2 of a change every couple of days. Gradually raise the pH to what is recommended for your species of puffer, and they will be more comfortable and healthier.
Once you track down the requirements for the species you have, I would be happy to offer any further suggestions or specifics.