GSP tank - BW to SW long term?

[bpb_21]

I've got a question about a setup for a GSP; currently the puffer in question is a juvenile (just under 2") and is in a low/medium salinity BW tank. I'm planning on setting up a spacious show tank for the puffer's long-term permanent residence. Therein is my question: how hard is it to convert from a brackish setup to a marine setup and actually keep your puffer alive during the process? I read Pufferpunk's article on GSPs on here and it suggested raising the salinity as the puffer grows, eventually reaching full SW. I'm assuming, due to the difference in bacteria found in BW and SW environments, that you'd have to re-cycle a tank at some point specifically for SW rather than just switching from a HOB filter to a protein skimmer all the sudden one day? (A little background - I've kept freshwater fish of all kinds for several years now, but haven't actually had a fully marine tank before so I'm new to that aspect.)
Also, with that in mind, what's the best tank setup as far as the scenery goes? I'm going for the estuary-look and was thinking of using aquarium sand as a substrate, but perhaps I should use aragonite or crushed coral as a substrate to help keep the pH in check? I'm also going to use faux-plants, as everything I read on these forums indicates that GSPs would just eat holes in real plans anyway (and not having to provide more intense full-spectrum light regularly should cut down on algae growth). Probably some driftwood, and plenty of rock-caves to hide in.
Basically, I was going to set up my show tank for the GSP's permanent home and then use the smaller tank it's presently in to experiment with my first marine environment, with different marine life. I'd hate to fumble my way through my initial marine tank with my GSP as the guinea pig! Will the (now) little guy (or girl) do fine in a brackish water tank over it's hopefully long lifespan, given all the above? Is any irreparable harm being done keeping it out of a marine environment when it's fully grown?

[Nick]

High brackish is fine for a lifetime, but marine is equally good for quality of life and allows use of skimmers and LR to reduce water changes and increase water quality. My GSP tank was slowly moved to full marine and never had a minicycle.

[bpb_21]

Interesting...so if you started with BW and slowly moved to full marine, how did your decor change? Did you incorporate live rock/coral/other marine features at some point in the process? Or was it just the same BW setup with changed water parameters? Just curious about the variation in the decor & life in the "typical" marine tank and the "typical" BW tank - which I equate more closely with FW.

[Boxermom]

I started with freshwater and went full marine. As I got close to full marine, I replaced the gravel substrate with crushed coral substrate, then replaced the plastic plants with artificial corals (slowly, over a period of months).

[Pufferpunk]

You can see my BW-SW 55g tGSP tank in the link below. I eventually added live rock & a skimmer.

[bpb_21]

That's a nice setup! Also I do really like the setups with the Fahaka in them; also, what is that root/rock/plant in the 29 gal F8 tank?
One question on the GSPs in the photos - are they actually "puffed" a little or just really hearty eaters? Do they tend to round out like that in adulthood? Mine's got a rounded stomach but is more oblong (but is also less than 2").

[Boxermom]

Mine has gotten less torpedo shaped and more Hindenberg shaped as he's gotten older and larger.