1.024 or 1.026, what's your preference and why?

[Grey Guy]

Not so true, as I show above.

Things have changed a lot in 30 years. In those days I just did what my lfs said to do and did not question it.

 

[Randy Holmes-Farley]

Things have changed a lot in 30 years.

What did I say that was 30 years old? (or wrong at any time???)

You are suggesting the saturation level of oxygen that I quoted has changed in 30 years?
The study I showed was from 2016.

 

[N.Sreefer]

35 ppt although I can see the argument for a lower specific gravity because the effects of osmosis would be lower and fish would have the easiest time with osmoregulation. Although randy posted a really interesting link that seems to debunk that idea.

 

[SaltwaterGuruNeeded]

Did you ever think about the fish that have never seen the ocean and have been kept at a lower salinity their whole lives? What would be better for them?

 

[fish farmer]

Yes, the fish in the ocean are slowly suffocating. lol

The tiny nugget of truth behind that claim is that O2 saturation is a teeny tiny bit higher at sg = 1.024 than at sg = 1.026. 6.89 mg/L O2 vs 6.79 mg/L O2.

That difference is very small, and there's no reason to assume the O2 is ever governed by the saturation level. It can be both higher (during the day ) and lower (at night).

LFS usually keep salinity lower because it is cheaper. Anything else (except hypo) is just an excuse, IMO.

Randy,

How does temperature factor into this? Doesn't lower temperature hold more Oxygen? So would high salinity at a lower temp hold more O2 than high temp and high salinity?

 

[arking_mark]

Things have changed a lot in 30 years. In those days I just did what my lfs said to do and did not question it.

I also recall the general rule of thumb was lower salinity for fish was less stressful.

 

[SaltwaterGuruNeeded]

Better question is how are you measuring it.

My hobby measuring tools don't do a great job (Hanna, GHL, Refractometer). I found this out and ended up crosschecking with a high-precision TM Hydrometer. Now I have confidence in my salinity and its at 1.0264 (automatically maintained through GHL).

Using a refractometer, but post is about salinity, not tools used to measure it. But was a good thought.

 

[SaltwaterGuruNeeded]

I also recall the general rule of thumb was lower salinity for fish was less stressful.

That's what my lfs said. Almost exactly.

 

[breakingakajav]

My water is usually ~1.025

I split the middle for all of my parameters. In case of anything, I have some level of tolerance.

 

[Randy Holmes-Farley]

Randy,

How does temperature factor into this? Doesn't lower temperature hold more Oxygen? So would high salinity at a lower temp hold more O2 than high temp and high salinity?

Yes, lower temps hold more O2 at any salinity.

That effect is bigger than the salinity effect we are talking about.

75 deg F, 35 ppt, O2 saturation is 6.9 mg/L
80 deg F, 35 ppt, O2 saturation is 6.58 mg/L
82 deg F, 35 ppt, O2 saturation is 6.47 mg/L

 

[Randy Holmes-Farley]

I also recall the general rule of thumb was lower salinity for fish was less stressful.

Yes, that "idea" has been around for decades, and in every salinity debate every year it comes up, but no convincing supporting data has ever been trotted out.

 

[N.Sreefer]

Yes, lower temps hold more O2 at any salinity.

That effect is bigger than the salinity effect we are talking about.

75 deg F, 35 ppt, O2 saturation is 6.9 mg/L
80 deg F, 35 ppt, O2 saturation is 6.58 mg/L
82 deg F, 35 ppt, O2 saturation is 6.47 mg/L

What about osmoregulation wouldn't they have to consume less water and filter less salt through their kidneys if the salinity is lower? Not disagreeing I'm just confused as to why a fish would prefer a higher salinity.

 

[gbroadbridge]

Did you ever think about the fish that have never seen the ocean and have been kept at a lower salinity their whole lives? What would be better for them?

35ppt.

For the first time in their lives they'll be happy and comfortable in water their metabolism was designed to work in.

 

[MuscleBobBuffPants]

Better question is how are you measuring it.

My hobby measuring tools don't do a great job (Hanna, GHL, Refractometer). I found this out and ended up crosschecking with a high-precision TM Hydrometer. Now I have confidence in my salinity and its at 1.0264 (automatically maintained through GHL).

Love my TM Hydrometer - I also have more confidence in my salinity measurements

 

[e3pillereefer]

How do you even know? I have three different ways to test salinity and they are all different. 1.024, 1.025, really? Thought my salinity may be high bc Hanna says so, even tho Apex says it's right on. Just got some snails and a few coral from a vendor in Cali and checked the salinity in one of the bags...was higher than mine. Really have no idea.

 

[N.Sreefer]

35ppt.

For the first time in their lives they'll be happy and comfortable in water their metabolism was designed to work in.

Not to be argumentative, I'm genuinely curious about this subject, do you know of any studies that support this claim? That would explain the results of the study randy posted a link to.

 

[ClearRain]

Some fish don't like the low salinity. Purple tangs, regal angels, lionfish are just a few that come to mind from work that prefer the higher salinity. They tend to not do as well in the lower salinity. Wherever your tank is happy is the best salinity.

 

[ying yang]

Im new to all this but my thinking at present is mother nature been doing this for millions or whatever years its been and try to replicate it as best we can and i see alot say want slice of ocean but some want to change it.
I get the unwanted pests thing as dont want spend lots money to just have bugs or 6 foot bobbit worm eat everything lol so currently im really struggling myself on what i actually want.
Do i want to start off with sterile tank and qt everything and remove all frag plugs or rocks corals come on as read this best but also read some successful tanks who try have everything in balance ( good and some of the bad) but anyway on salinity i would think 1.026 be best but do get if just fish only lowering salinity could ve option but i got reef tank so no need me research anymore than i already done on lower salinity ^_^

 

[DrZoidburg]

In spirit of thread keep main tank at 1.024, second at 1.025, third at 1.025-1.026. When the little tanks that don't have over flows hit a bit over 1.026. Which is usually about 1.5 wk with some topping off. I take water from the previous ones. Mix new at 1.024 for main. If you wanted to be really regional species specific salinity might matter. Ex: Corals from the Red Sea come from higher salinity.

 

[Jbell370]

1.026 cause that is 22 scoops of TM in my water mix tank.