Higher salinity in collected natural seawater... Do I need to adjust?

[russell.dexter]

Hi guys,

Back in the hobby after a seriously long hiatus - so practically a noob now.

Have a question on using NSW for my pico. (It's a 5g Fluval evo that I perform a 90% water change on weekly)

The natural sea water I collect here in Nassau has a salanity of about 1.028 - 1.029 when I measure it during collection - but I'm beginning to realise the standard for you guys in the hobby is about 1.026

I have just cycled the tank and put in some zoa and GSP frags- and they are all beginning to open.... But is the salinity in my tank too high for long term health?

Throughout the cycle I have kept it at 1.028 with manual distilled top ups daily, but should I be mixing with distilled after I collect and slowly bring the range down in the tank?

Any obvious benefits to tinkering constantly or is it better to just let everything acclimate to my 1.028 and have to worry and work less when I collect my water?

Thanks for the help!
Dexter

 

[Saltyreef]

What are you using to measure salinity?

 

[russell.dexter]

What are you using to measure salinity?

An old fashioned swing arm hydrometer. Alas, it once was standard equipment. I picked one up when I set up the nano.

I do have a generic refractometer on mail order - the lfs here doesn't carry any.

Could it just be reading too high?

 

[Cory]

Dont worry what the salinity reads. Just use it. Dont collect after a big rain storm it will be lower. Probably your swing arm is off and its actually closer to 1.026. If i had nsw near me i would use it no questions asked.

 

[Saltyreef]

Agreed with above comments.
The swing arm is likely reading high.
Wouldnt hesistate to use that NSW either.
Would love to collect more than NSW myself over in your neck of paradise!!
Happy Reefing!

 

[fishybizzness]

I agree with the other posts that your refractometer is probably inaccurate. I also use nsw in the Caribbean and it is always dead on 1.026. Its free and better imo than any artificial salt water out there. I collect it 50 gallons at a time!

 

[Randy Holmes-Farley]

I'd be very surprised if it is really is sg = 1.028 to 1.029, but it might be. That is well above the whole ocean average of 1.0264.

 

[russell.dexter]

Thanks everyone!

I will let you know what the 'true' reading is when the refractometer arrives, but for now I will just focus on keeping the salinity stable at "1.029"- (my next mail order is an ato, lol) @Randy Holmes-Farley, I am interested to see if it's a 'true' reading as well.

The zoas are open this morning and the GSP is starting to open- (I added them two days ago,) so I will take that as a good sign

Agreed on the NSW @fishybizzness I have some salt mix just in case there is a time when I can't collect from the ocean- but I figure it's super clean and very free-and being a 5 gallon setup I can do a 90% change weekly with a single five gallon bottle I take when snorkeling

 

[threebuoys]

Make sure you tap the swing-arm hydrometer a few times to get air bubbles off of it or it will read high. Several months ago I ordered a refractometer on Amazon and It read way too low. Had to return it. Most swing-arms are accurate, but more tedious to use. I live on the Outer Banks of North Carolina and I use NSW to calibrate my conductivity meter. It is right on target at 1.026. (The conductivity meter I bought read too low also when I first used it). My swing-arm has been accurate throughout.

 

[russell.dexter]

Make sure you tap the swing-arm hydrometer a few times to get air bubbles off of it or it will read high. Several months ago I ordered a refractometer on Amazon and It read way too low. Had to return it. Most swing-arms are accurate, but more tedious to use. I live on the Outer Banks of North Carolina and I use NSW to calibrate my conductivity meter. It is right on target at 1.026. (The conductivity meter I bought read too low also when I first used it). My swing-arm has been accurate throughout.

Thanks threebuoys,

Water collection and change again this weekend. I always collect on an incoming tide away from the shore. I am going to triple check my readings, tap thoroughly and reply to this thread.

 

[fishybizzness]

Let us know how it goes!

 

[Randy Holmes-Farley]

Most swing-arms are accurate, but more tedious to use.

Are they?

The ones I tested were a mixed bag:

Chemistry and the Aquarium: Specific Gravity: Oh How Complicated!

This month, Randy explains and reviews specific gravity.

reefs.com

"So how do these hydrometers measure up? In my tank the water was measured to be S=35 ± 0.5 by conductivity. Using the Deep Six swing arm hydrometer I got readings of S=32.5 ± 0.5 at 81 °F and S=32 ± 0.5 at 68 °F. Using the SeaTest I got S=34.5 ± 0.5 at 81 °F and S=34 ± 0.5 at 68 °F."

 

[threebuoys]

Are they?

The ones I tested were a mixed bag:

Chemistry and the Aquarium: Specific Gravity: Oh How Complicated!

This month, Randy explains and reviews specific gravity.

reefs.com

"So how do these hydrometers measure up? In my tank the water was measured to be S=35 ± 0.5 by conductivity. Using the Deep Six swing arm hydrometer I got readings of S=32.5 ± 0.5 at 81 °F and S=32 ± 0.5 at 68 °F. Using the SeaTest I got S=34.5 ± 0.5 at 81 °F and S=34 ± 0.5 at 68 °F."

You're right Randy, I shouldn't have extrapolated that conclusion so quickly. To correct myself......

I have had great difficulty in finding hobby grade equipment that reliably measure salinity without confirmation / calibration using accurately prepared or purchased samples. 45 years ago, I used float hydrometers because that's what my LFS owner recommended. Recently I've been disappointed in a number of products I've purchased. Of those, I have been most confident in the Instant Ocean Swing-Arm Hydrometer because it correctly read the salinity of the Atlantic Ocean several hundred yards away from my house at the Cape Hatteras National Seashore to be 1.026 Sg, 35 ppt at 78 degrees F. The only time I got a suspicious reading from the swing-arm I'm using, I had not adequately bumped the tiny air bubbles off of the arm resulting in too high a reading. I have taken multiple samples from the shore more than 20 miles from the nearest inlet, giving me confidence the water has not been diluted by less salty water flowing out of the Pamlico Sound. My technique is probably a little looser than it should be, and I probably have an error factor of +/- 0.5 salinity, maybe more. Since the other devices I checked were off by as much as 9.0 salinity, I was relieved to find something that made sense.

I have now used the NSW to calibrate a conductivity tester with the hopes to have a faster way to check behind myself to keep salinity in check. I did not buy the Hanna checker but chose a cheaper version on Amazon. That could be a decision I later regret, only time will tell.

A general concern I've come to have is that almost all of the hobby grade testing equipment available have flaws of which the hobbyist needs to be aware. And, that anytime something doesn't make sense, he should consider if factors other than the obvious might be contributing to the situation.

My a-ha moment came when I tried to mix 125 gallons of saltwater to a Sg of 1.026 for my first tank in over 35 years. After following the instructions on the Instant Ocean Bucket, my refractometer read 1.019, so I started adding more salt. The reading eventually got to 1.021 when I realized I would run out of salt long before I reached 1.026. So, I ordered the swing-arm from Amazon ( the nearest LFS is 120 miles away) waited several days for it to arrive, and then determined I had raised the Sg to almost 1.30! Since joining R2R, I see the challenges with other testing equipment ( e.g. API ammonia) that add to the confusion. I'll step down from that soapbox.

Thanks for your contributions to the hobby and to R2R. I've read many of your articles and I find them most helpful.

 

[Cory]

Fwiw a sg of 1.028 is perfectly fine for the animals in the Red Sea. Anthias come from there.

 

[russell.dexter]

Hey guys,

Water change weekend and I've trippled checked my readings (and triple tapped).

Still getting a high reading - about 1.028. And right in line with readings since I started the pico.

This is collected water on an incoming tide.

As I do a 90% or so water change every week- and everything seems happy - I will not tweak and aim for stability instead.

I have mail ordered a refractometer and will revert with my measurements after I get it here in a week or so. I'll make the assumption that the swing arm hydrometer is off until then.

 

[Cory]

Hey guys,

Water change weekend and I've trippled checked my readings (and triple tapped).

Still getting a high reading - about 1.028. And right in line with readings since I started the pico.

This is collected water on an incoming tide.

As I do a 90% or so water change every week- and everything seems happy - I will not tweak and aim for stability instead.

I have mail ordered a refractometer and will revert with my measurements after I get it here in a week or so. I'll make the assumption that the swing arm hydrometer is off until then.

Id use that. Even if it was 1.028, thats perfectly fine for fish and corals. The red sea is that and higher.

 

[Randy Holmes-Farley]

If it is really that high, why not add a little of your top off water into it before use?

 

[russell.dexter]

If it is really that high, why not add a little of your top off water into it before use?

Thanks Randy,

I plan to- I just want to wait until the weekend when my refractometer comes to double check the reading. I'm afraid that the swing arm may just be reading high. Everything 'seems' happy (polyps open etc....) so I will aim for stability at the "1.028" and once I get confirmation that the reading is inaccurate I will just adjust my NSW collection every week accordingly to a nice 1.026.

Thanks a lot for all the feedback, and your articles that I have been reading!

 

[fishybizzness]

Just posted in another thread. This is the parameters of the saltwater i collect off the beach.

Salinity- 1.026 - Millwaukee refractometer.
Nitrate- Undetectable-Red Sea
Calcium- 400- Red Sea
Magnesium- 1440-1450- Red Sea
Alkalinity- 7.3- Hannah
Phosphate-.02- Hannah.

 

[russell.dexter]

Just posted in another thread. This is the parameters of the saltwater i collect off the beach.

Salinity- 1.026 - Millwaukee refractometer.
Nitrate- Undetectable-Red Sea
Calcium- 400- Red Sea
Magnesium- 1440-1450- Red Sea
Alkalinity- 7.3- Hannah
Phosphate-.02- Hannah.

Both my refractometer and salifert tests arrive by the weekend...I hope to post a synopsis like this on Sunday night.

Collection site is here. Perhaps the salinity is a bit higher because it is in sort of a cove.

I guess the refractometer and tests will tell me what I need to know