Which salinity reading would you trust more

[Anonymous]

Like Bry said, I'd be curious to see what a plastic hydrometer read for you. That's quite a difference in reading.

 

[GSchiemer]

If you want to really know what the answer is, do what I do....


Use a good old swing arm hydrometer.

I will let you borrow mine if you want, been using it for years, nary a problem yet. Although sometimes it gets really full of salt and gunk and I have to clean it out before using it....

I don't mean to be contrary, but in IME and in my testing of swing-arm hydrometers, I found them to be very inaccurate. There were almost no two alike! Even if you happen to get the one that is accurate initially, they do not maintain their accuracy over time. Now Seatest did improve their model after my scathing product review a few years ago, but I would never trust one of these as the sole source of measuring specific gravity. If you do use one, you should test it against a refractometer and write a correction factor on the side of the unit. This error correction factor will have to be re-check every few months because, as I said, the readings will shift over time.

Greg

 

[Anonymous]

Thanks guys,

Just to clarify, I am not doing this to determine which to use over time. I am trying to decide which is more accurate due to the difference in readings - I want to figure out if I need to add salt or not.

 

[cygnus]

best to me more worried about consistancy than accuracy, granted both are important, but with consistancy you can adjust/mathematically for the lack of accuracy. Or you can just get a volumemetric beaker of pure H2O at 4 degrees C. Put in 35 grams of NaCL and bring the water level up to 1000 ml. that will give you a salinity reading of 1.025, But since we are dealing with living systems that are quite adaptable we can get away with a wide range 1.020 to 1.030. It is drastic changes that do the damage. Better to keep your temp at 82, rathar than have it flux between 75 and 82 thru out the day. The same applies to some degree for water chemistry.

 

[Anonymous]

Cygnus:

:welcome:

Good stuff. I agree with you, I am trying to figure out if my salinity has been whacked but stable, or accurate and stable.

 

[Anonymous]

Righty,

Don't forget that the refractometer has to be used at a consistent temperature to be accurate (calibrated and used at 25 degrees celsius I think). Anthony Calfo says he doesn't use them in his coral houses as humidity and high temperature will reduce their accuracy.

I'd be inclined to trust the pinpoint monitor.

Tom

 

[Anonymous]

Can you get a second opinion? Get a buddy to check with their gear.

 

[Anonymous]

If you want to really know what the answer is, do what I do....


Use a good old swing arm hydrometer.

I will let you borrow mine if you want, been using it for years, nary a problem yet. Although sometimes it gets really full of salt and gunk and I have to clean it out before using it....

I don't mean to be contrary, but in IME and in my testing of swing-arm hydrometers, I found them to be very inaccurate. There were almost no two alike! Even if you happen to get the one that is accurate initially, they do not maintain their accuracy over time. Now Seatest did improve their model after my scathing product review a few years ago, but I would never trust one of these as the sole source of measuring specific gravity. If you do use one, you should test it against a refractometer and write a correction factor on the side of the unit. This error correction factor will have to be re-check every few months because, as I said, the readings will shift over time.

Greg

Although I only use a swing arm hydrometer (because I am cheap) I completely and totally one hundred percent agree with you. I also grok your use of the word scathing. I gave an insurance agent a scathing review of her insurance company just this very night

 

[GSchiemer]

Righty,

Don't forget that the refractometer has to be used at a consistent temperature to be accurate (calibrated and used at 25 degrees celsius I think). Anthony Calfo says he doesn't use them in his coral houses as humidity and high temperature will reduce their accuracy.

I'd be inclined to trust the pinpoint monitor.

Tom

Most refractometers have either automatic or manual temperature compensation built into the unit, so this shouldn't be a factor.

Greg

 

[Anonymous]

Righty,

Don't forget that the refractometer has to be used at a consistent temperature to be accurate (calibrated and used at 25 degrees celsius I think). Anthony Calfo says he doesn't use them in his coral houses as humidity and high temperature will reduce their accuracy.

I'd be inclined to trust the pinpoint monitor.

Tom

Most refractometers have either automatic or manual temperature compensation built into the unit, so this shouldn't be a factor.

Greg

Really? Interesting. I didn't know this.

 

[Anonymous]

ATC = Automatic Temperature Compensation. If you've shopped for Refractometers you've seen the term ATC Refractometer.

 

[Anonymous]

ATC = Automatic Temperature Compensation. If you've shopped for Refractometers you've seen the term ATC Refractometer.

Seen, not understood and ignored? Maybe. Not always the most intelligent shopper, me...

 

[Anonymous]

You're a "Hunter". Focus on the target even if there's a tree falling on you. :lol:

 

[Fastmarc]

... and i KNOW for a fact my pinpoint PH meter would fluxuate up and down when my chiller would cycle on.

This brings up a point I forgot to mention.
When testing your water sample, remove it from the tank (put in a glass, etc.) as electrical interference from lights, pumps and yes, chillers could interfere with the readings.
In my case, my lights does, but that is easily neutralized by checking in a test tube.

 

[tinyreef]

that sounds suspiciously close to "grounding your tank". uh-oh.

 

[Fastmarc]

that sounds suspiciously close to "grounding your tank". uh-oh.

Not really. Even if the tank is grounded (as is the case of mine and other's I have been in discussion with) this problem occures.

 

[Anonymous]

... and i KNOW for a fact my pinpoint PH meter would fluxuate up and down when my chiller would cycle on.

This brings up a point I forgot to mention.
When testing your water sample, remove it from the tank (put in a glass, etc.) as electrical interference from lights, pumps and yes, chillers could interfere with the readings.
In my case, my lights does, but that is easily neutralized by checking in a test tube.

I never thought about that. Makes good sense, thank you!

 

[tinyreef]

that sounds suspiciously close to "grounding your tank". uh-oh.

Not really. Even if the tank is grounded (as is the case of mine and other's I have been in discussion with) this problem occures.

actually, i was just kidding. trying to incite another controversial discussion.

 

[Anonymous]

You're a "Hunter". Focus on the target even if there's a tree falling on you. :lol:

A very kind way to say "impulsive shopper". :lol:

 

[magicman76]

have you thought about getting a cheap brewery glass hydrometer? Ive heard there extreamly accurate and Ive seen them for like 5 bucks online.
just to throw another measurment into the pot..