Bringing up Salinity

[GSP 3]

Well today i finally stopped being irresponsible and went and bought a hydrometer for my gsp's tank. I was surprised to see the salinity of the water is barely 1.008. My puffer is almost two years old so i think i'm going to aim to move up to 1.014. Does this sound right? and if so how much can i raise the salt by per water change, as in what should the salinity of the new water i'm putting in be (i do 25% water changes weekly).Thanks all p.s. i think this may be why my puffer hasn't been growing very quickly!

[jmiller]

No more than .002 per week or you risk killing the beneficial bacteria.

[fvbump82]

I agree with jmiller. But I would suggest you eventually end up at 1.022 specific gravity (raising it as suggeted by jmiller) so that your GSP will eventually be in full SW conditions. What I read is that they will survive longer at full SW rather than to keep them at brackish levels for life.

[RTR]

The change-over from FW nitrufication to SW nitrification is somewhere from 1.007 - 1.008 to around 1.012 - 1.014. In that range you need to be very cautious with changing the specific gravity and must check routinely to see if there are any signs of ammonia or nitrite. If such are showing, you need to hold at that level until they clear and be very careful not to move up more than 0.002 in any change. You cannot afford to kill the FW bugs before the SW bugs can handle all the nitrogen metabolites. Beyond those levels you should still check, but you are unlikely to have problems.

The reason that GSPs do better in full marine is not the specific gravity itself. It is that we can rum full marine tanks cheaper and cleaner for long periods of time. We can use live rock to make the tank run w/o other biofiltration (no ammonia, nitrite, nitrate build-up) as FOWLR (fish only with live rock), and also operate a foam fractionator/skimmer to dump waste without massive water changes, and even add a 24/7 lighted macroalgae refugium to absorb wastes and generate 'pods to help feed the fish and scavenge small wastes. None of that trio of super techniques will operate effectively below light marine levels (~1.021). It is the specialized techniques that we have available under marine conditions that allow the fish to live out its full lifespan, not just the salt density itself. If you still use convention biofiltration and large scale water changes only, the fish will not necessarily live long than it would at mid-level BW, and the total operations cost would be higher. The capital costs of the SW techniques over the life of the fish are less than the costs of the marine mix itself over the same period of time.

HTH