Reef Discussion

[ryan1986]

Ok so i know the salt mix is meant to be 1.025-1.026 /35ppt I had a floating hydrometer but I don't trust them as far as I can throw them so i bought a redsea refractometor. Was wondering if anyone can help me work out if its reading is correct or out as atm its saying my salt is approx 1.030 /40ppt just don't want to dump water to bring it down to the right level to find its actualy off and reading high.

P.s I'm in south east Melbourne if anyone wants to drop past and try their refactometer and see how it reads.

 

[macca_75]

Did you calibrate it first? Just put some RO onto it - it should read 0.0 - this will be close enough for calibration for our purposes.

 

[ryan1986]

Did you calibrate it first? Just put some RO onto it - it should read 0.0 - this will be close enough for calibration for our purposes.

Na I didn't. I thought they came pre set. But ill do that before I use it.

 

[ryan1986]

Did as you said and used freshwater. And adjusted. Was about 5ppt out so looks like my salt is about 1.024-1.025 at 25°c so I'm happy with that.

 

[NiCd]

You can also make up a reference solution with sea salt if you have an accurate pair of scales, just make sure you dry it in the oven before weighting it.

 

[ajkdark]

Calibrate the Red Sea Refractometer with RO water to zero, every time you use it.

That will give you a solid reading

 

[NiCd]

RO will make sure you get consistent readings on your particular device, but you should be calibrating off a reference that is closest to your target reading if you want that reading to be accurate to what it actually is.

The errors refractometers have are not linear, a true reading at 1.00 does not equate to a true reading at 1.025, likewise a true reading of 1.025 does not mean a true 1.00 reading

For lab spec you are meant to calibrate to a low, mid and high reading. unless you are going to be doing hypo we can just work on a mid-reading.

35g of sea salt flakes in 1000g of RO will give you 35ppt or 1.026, you can purchase multi reference solutions are are a lot better than this method and help you check other gear

https://www.sewatec.de/ati-reference-1000-ml.html

I believe FM has released an even better one with phos, nitrate and a few trace elements as well

BRS did a good video last year with some other tips about getting the most accurate readings

 

[Savage Henry]

Once you have your refractometer calibrated you can test the water from Port Philip Bay and use that as a reference thereafter (with provisos, i.e. don't test immediately after rain etc).