Optimal Salinity Level 33ppt or 35 ppt?
- Thread starter livinlifeinBKK
- Start date
- Tagged users None
blaxsun
10K Club member
Personal preference I guess, or they have some reef inhabitants that require a lower salinity. There's not really any wrong answer. I like to run my tank @ 35ppt (1.0265) and others will run in a range from 33-34 (1.0249 to 1.0256). Or they're cheap and don't like spending money on salt. 
Last edited:
OP
OP
livinlifeinBKK
5000 Club Member
Could it have any negative effects on any typical reef tank inhabitants? The reason I'm considering lowering mine to 33 ppt is because I'm concerned my refractometer may be off and I won't be able to take it to a shop for a few days at least...If it is off, I'm 99% sure it's testing low meaning I'm making my water hyper saline...I was just thinking until I can figure it out definitively maybe I should run the tank at 33ppt (well what my refractometer tells me is 33ppt) since if it is off it would at least be closer to the correct salinityPersonal preference I guess, or they have some reef inhabitants that require a lower salinity. There's not really any wrong answer. I like to run my tank @35ppt (1.0265) and others will run in a range from 33-34 (1.0249 to 1.0256). Or they're cheap and don't like spending money on salt.
blaxsun
10K Club member
Only if it's a really abrupt swing one way or the other. Whenever one performs a water change you're going to see a slight swing (even using rocket science). In my tank the salinity will typically swing between 34.5 and 35.0, depending on what kind of maintenance I'm performing. I have a Neptune probe that monitors in near real-time, so even when it shows a drop in reality it probably takes a few hours for the tank to completely shift.
A happy medium might be reducing it to 34ppt or 33.5ppt - just so you have a bit of margin built-in either way.
A happy medium might be reducing it to 34ppt or 33.5ppt - just so you have a bit of margin built-in either way.
OP
OP
livinlifeinBKK
5000 Club Member
Ok, and for a nano tank what's the best way to do this? I think I heard that siphoning out a little of the tank water and letting the ATO fill with RODI water is the safest way...Also, how slowly should I lower the salinity if it's only going to be about a 1.5ppt decrease?
blaxsun
10K Club member
That's usually the easiest, yes. I'd figure out how much you need to remove <insert math here>, and probably adjust that every 6 hours or so over a few days. It's probably overly cautious, but in the event your salinity is really off I'd probably err on the side of caution.
OP
OP
livinlifeinBKK
5000 Club Member
So 6 hours for every 1.5ppt? And as soon as I find out how off my refractometer is, do that over however many days it takes to reach the correct salinity, am I understanding you right?
Lavey29
10K Club member
I actually recently discovered I was running at 33 when I thought it was 35. Milwaukee digital refractometer was off due to using RODI for calibration instead of distilled. All this time it was showing 35 but really was only 33 and everything seemed OK. After correcting it last month I'm now at 35 or 1.026.Personal preference I guess, or they have some reef inhabitants that require a lower salinity. There's not really any wrong answer. I like to run my tank @ 35ppt (1.0265) and others will run in a range from 33-34 (1.0249 to 1.0256). Or they're cheap and don't like spending money on salt.
OP
OP
livinlifeinBKK
5000 Club Member
Everything in the tank seems to be doing ok...although I don't have much in there atm...I'm mainly concerned about my microbiome which I've really been working hard to diversify and boost...idk how sensitive the microfauna and many bacterial strains are
blaxsun
10K Club member
I meant spread the 1.5ppt out over 2 days, so 0.1875ppt every 6 hours. The easiest is just to figure out <insert math here> how much water you need to remove to get to get to 33.5ppt, then divide by 8 (or however many increments you want to perform this over).
OP
OP
livinlifeinBKK
5000 Club Member
Ok, I understand now...I really hope my refractometer isn't too far off...I had a woman who worked in a shop test it using their tank water and it came back at exactly 25 ppt when she said it should be 35ppt which is a little odd that it would be off by exactly 10ppt unless the guy who first calibrated it for me made a big mistake. I then ordered a digital salinity meter which was supposed to come calibrated by the company I ordered from and it showed my water testing the same as the refractometer. It wasn't the best shop though and I don't think the girl watching the store knew whether or not they ran their salinity lower as some other shops do. Another shop I bought a fish from a week or so after put water in the bag which I measured to be 29ppt with the digital meter so honestly I find it hard to believe both the traditional refractometer and digital refractometer were both off by the exact same margin. I think the shop probably was running their water with low salinity and the shop girl just was unaware.
OP
OP
livinlifeinBKK
5000 Club Member
That's what I thought...I'm hoping I haven't been off by much if any...with some of the forums I've read on here though, I should really order the calibration fluid myself just to be sure though
