SG for FOWLR poll

[mling]

What do most people with FOWLR keep their SG at ?

I hear that the lower, the better, but that will cause problems with the inverts.

 

What do you do if you don't have inverts in FOWLR tanks ?

i.e. who / what does the "work" the inverts do ?

[yauger]

What do most people with FOWLR keep their SG at ?

I hear that the lower, the better, but that will cause problems with the inverts.

 

What do you do if you don't have inverts in FOWLR tanks ?

i.e. who / what does the "work" the inverts do ?

 

Well, most reefers I know keep their tanks at 1.025, I personally keep mine closer to 1.026. I believe the natural sea water is closer to 1.027 SG so I'm sure if your close to that your fine. Now if your talking about a hypo SG tank for treatments of something like ich or something or that nature I would only suggest it in a separate tank...

For the inverts issue in your tank you can get any herbivore fish that will graze on most algae that will grow for example a lawnmower blenny or some tangs would do the trick...

Good luck...

[davelin315]

I used to have a FO that didn't have live rock in it, but there's not much of a difference... I would run it between 1.017 and 1.019. You may or may not have the inverts survive in there with that, I wouldn't say for certain that they'll all die. For instance, I think that hermit crabs will survive that, not sure about all snails, though, you'd have to acclimate slowly. I would be careful, though, of picky eaters fish wise. You never know what might throw them off.

 

For hyposalinity you could run all the way down to 1.009, but then you'd definitely lose the inverts.

 

As far as maintenance, water changes and vacuuming any substrate is the key. When things got covered in algae, I would always take them out and bleach them (that was in the days of dead coral being popular decorations). One reason you shouldn't have the same problems is that in a FO or a FOWLR you don't need the same type of lighting so it's easier to prevent the nuisance algaes from even starting up.

[yauger]

Dave what is the point for running the tank at such a low salinity? Proper maintenance and care along with some good hardware should prevent any nasties that might pop up... but if its unnatural to the fish it can't be good for them long term...

[treesprite]

Before inverts 1.019. Since inverts 1.025.

[Rascal]

Dave what is the point for running the tank at such a low salinity? Proper maintenance and care along with some good hardware should prevent any nasties that might pop up... but if its unnatural to the fish it can't be good for them long term...

 

That logic makes sense to me, but from what I've read there are two factors at work that make lower SG better for fish. The first is that fish actually have to expend energy to keep their bodies at equilibrium with the surrounding water. When the SG is lower it is easier for them to do this and therefore less stressful. The second is, as you mentioned, the "nasties" can't tolerate the lower SG as well if at all, which further gives an edge to the fish. I think you will find that most LFS keep their fish systems at a low SG for these reasons. I always ask for that info when I'm buying something so I have an idea of how long I need to acclimate it.

 

This article explains it better than I could:

 

Marine teleost fish (higher bony fishes) maintain their osmotic concentration at about one quarter to one third that of sea water. In normal sea water, these fish have a tendency to lose water from their gills due to osmosis and also in their urine. Fish have to drink a lot of water to make up for the loss, however, as the water contains a lot of salt (35‰) they must remove the excess salt from their system. The sodium and chloride ions are secreted by the gills and magnesium and sulphates are excreted in urine. This is an active process and requires energy much like the energy required to keep warm blooded animals warm.

 

When fish are under stress, one of the processes that is affected is ion regulation. This means they have difficulty adjusting the concentration of ions (sodium, chloride, etc.). Lowering the salinity of the tank water makes the concentration of ions closer to that of the fish"s internal fluids and reduces the fish"s efforts to maintain the correct concentrations.

Edited August 9, 2007 by Rascal

[treesprite]

good information, Rascal

[yauger]

That logic makes sense to me, but from what I've read there are two factors at work that make lower SG better for fish. The first is that fish actually have to expend energy to keep their bodies at equilibrium with the surrounding water. When the SG is lower it is easier for them to do this and therefore less stressful. The second is, as you mentioned, the "nasties" can't tolerate the lower SG as well if at all, which further gives an edge to the fish. I think you will find that most LFS keep their fish systems at a low SG for these reasons. I always ask for that info when I'm buying something so I have an idea of how long I need to acclimate it.

 

This article explains it better than I could:

 

Marine teleost fish (higher bony fishes) maintain their osmotic concentration at about one quarter to one third that of sea water. In normal sea water, these fish have a tendency to lose water from their gills due to osmosis and also in their urine. Fish have to drink a lot of water to make up for the loss, however, as the water contains a lot of salt (35

[alan mcilvried]

I keep mine at 1.021 and my crabs, shrimp, snails and mushrooms all are happy.

[extreme_tooth_decay]

I'd go 1.017-1.019.

 

I recall Dr. Mac telling me that's the neighborhood he runs his fish at.

 

tim

Edited August 10, 2007 by extreme_tooth_decay