The Puffer Forum

I honestly can't say I know for sure what purigen removes or doesn't remove, other than that it seems to:
1) Polish my water a bit
2) Keep the nitrates in my large saltwater tank down for longer
I'm pretty sure that whatever it does, it won't harm the nitrogen cycle in an established tank - I've never used it in a new tank, and it's never caused issues in either of the well established tanks I've used it in, so I know that it's safe under those conditions for sure.

Sure, but what happens if you stop using it?

The only way to remove nitrates without water changes or massive plant use is to stop them from being produced in the first place, by removing the ammoina source. Remove the ammoina source and you starve out the bacteria.

I only use Purigen on my reef tanks, to reduce chemical warfare between corals.

Yeah, but if you are using a skimmer already, that's removing the wastes and protiens already.

Update:
Sg=1.012
pH=~7.8
Ammonia=0
Nitrite=0
Nitrate=~5

I waited, watching a few days to be sure that Gollum didn’t get sick, then continued raising SG. The remainder of the raise happened using the same old hydrometer, and since it was reading my tap water as anywhere between 1 and 1.004, there may have been some inconsistencies. I finally got my refractometer from ebay yesterday, so the numbers above from this morning should be accurate. There are only two shrimp left alive in the tank, so Gollum has been productive. He’s just as plucky as he has always been. It was sad to lose our newer puffer, but since the tank is only 45 gallons, we’re going to keep Gollum alone in there from now on (well, him and his occasional live foods). He’s only about 1.5 inches now, but when he’s reached his full 6”, I think the size of the tank will suit him well.

I went back to the LFS and took a look at the tank I got the other puffer from. Most of the puffers looked okay, but there was one who seriously looked bad. Instead of nice and plump, from his midpoint back he was totally sunken in and had almost no mass to him. We asked about him, and the clerk didn’t know what was wrong, but one good thing happened. I don’t know if it was from my comments, or if they had been planning to do it anyway, but when I went back, they were in the process of raising SG in their GSP tank as well! They have been helpful, and certainly more knowledgeable about aquatics than the local chain pet store, so I think I will continue to shop there for all my fishy needs. Now I just have to work on them to stop stocking those painted fish.

Thank you all for your help through everything. I've definitely become a life-long member.

Great job getting him through that!

And we're very glad to have you stay.