Puffer Newbie...Gravel tank and sand mix?

[PufferNewbie]

Hi. I've read a lot in these forumms, and you all seem so knowledgable. This is the second time I've had a tank with puffers. I have an exclusive tank now with both spotted and F8 puffs. As long as they are well fed, they are not bothering each other at all. Matter of fact, one F8 and Spotted Puff hang out together. . I apologize for leaving out the numbers on the water properties in the tank, but it is currently only gravel with a low salinity as my puffers came from fresh water tanks, and I am using a VERY slow drip method to add sea salt. They are sprite and happy. I want to add sand, only because I've read this is what they should have, although I'm not sure why. Is sand a must? I have a lot of pieces in the tank for them to 'claim' as their own, and other places to hide. They sleep well at night with a low light from my t.v. (bad habit of leaving it on). I'm just wondering, if they are thriving, should I fix what isn't broken, or will I pay for it later? Thanks, guys!

[Pufferpunk]

Substrate for BW fish should be aragonite sand, to buffer the pH at a steady 8. Eventually, your GSP will grow 3x the mass of the F8 & become much more aggressive. Also, the F8s are best kept at low BW (1.005) & the GSPs, high BW-SW.

[PufferNewbie]

Good grief! You'd think the folks that sold me these fish would know their stuff. I was under the impression they would grow to about the same size and could co-habitate, unless of course, they are hungry and/or cramped. Sigh....thank you! I guess I have some work to do. So helpful!

[Pufferpunk]

They never do! Never believe the folks making $$$ off you to give good advice.
viewtopic.php?f=68&t=28469
viewtopic.php?f=68&t=28692

[bertie 83]

These fish shop peops generally don't know, or just wanna sell sell sell. Gsp need min 30g each, f8 15g min each. The different water required is detailed by pp above.

[sgtmyers88]

It has been stated that there has been some success in keeping figure 8 and green spotted puffers together but its likely because they are still young as PP stated in her article. You may be able to get away with the current living arrangements for now but I would suggest a 55-75 gallon tank for your GSP's. Craigslist often has people selling complete setups from 100-300 bucks. Also when you take them to high brackish to marine salinities they will appear brighter in coloration be healther and may even experience a spike in growth. (one of mine spiked from 2 inches to 4 inches in a couple months!)