Help! Salinity Reading Issues

clean and calibrate the refractometer.
use RO/DI water to rinse the glass slide and cover on the refractometer first to be sure there is no salt residue. once that is done put a fresh drop of RO/DI water on the slide and calibrate the reading to 1.000

 

Okay, I'll try calibrating it again. I did rinse the slide with tap instead of RO/DI, so maybe that will make a difference.

 

nope, less oxygenation in distilled water for one thing... the waters boiled of any contaminates and in doing this releases the oxygen...

here sourced from a great read: Water quality- different water filtration methods- Reverse Osmosis/ Distillation/ Ion Exchange/ Carbon

It explains how deionization works, etc. But here is the quick summary of distillation versus RO

[FONT=Geneva,Helvetica,Arial]Distillation[/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]Distillation is probably the oldest method of water purification. Water is first heated to boiling. The water vapor rises to a condenser where cooling water lowers the temperature so the vapor is condensed, collected and stored. Most contaminants remain behind in the liquid phase vessel. However, there can sometimes be what is called carry-overs in the water that is distilled. Organics such as herbicides and pesticides, with boiling points lower than 100 °C cannot be removed efficiently and can actually become concentrated in the product water. Another disadvantage is cost. Distillation requires large amounts of energy and water.[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]Distilled water can also be very acidic, having a low pH, thus should be contained in glass. Since there is not much left, distilled water is often called "hungry" water. It lacks oxygen and minerals and has a flat taste, which is why it is mostly used in industrial processes.[/FONT]

[FONT=Geneva,Helvetica,Arial]Reverse Osmosis[/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]Reverse osmosis (RO) is the most economical method of removing 90% to 99% of all contaminants. The pore structure of RO membranes is much tighter than UF membranes. RO membranes are capable of rejecting practically all particles, bacteria and organics >300 daltons molecular weight (including pyrogens).[/FONT] [FONT=Verdana, Arial, Helvetica, sans-serif]In fact, reverse osmosis technology is used by most leading water bottling plants.[/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]Natural osmosis occurs when solutions with two different concentrations are separated by a semi-permeable membrane. Osmotic pressure drives water through the membrane; the water dilutes the more concentrated solution; and the end result is an equilibrium. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]In water purification systems, hydraulic pressure is applied to the concentrated solution to counteract the osmotic pressure. Pure water is driven from the concentrated solution and collected downstream of the membrane. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]Because RO membranes are very restrictive, they yield slow flow rates. Storage tanks are required to produce an adequate volume in a reasonable amount of time. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]RO also involves an ionic exclusion process. Only solvent is allowed to pass through the semi-permeable RO membrane, while virtually all ions and dissolved molecules are retained (including salts and sugars). The semi-permeable membrane rejects salts (ions) by a charge phenomena action: the greater the charge, the greater the rejection. Therefore, the membrane rejects nearly all (>99%) strongly ionized polyvalent ions but only 95% of the weakly ionized monovalent ions like sodium. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif] Reverse osmosis is highly effective in removing several impurities from water such as total dissolved solids (TDS), turbidity, asbestos, lead and other toxic heavy metals, radium, and many dissolved organics. The process will also remove chlorinated pesticides and most heavier-weight VOCs. Reverse osmosis and activated carbon filtration are complementary processes. Combining them results in the most effective treatment against the broadest range of water impurities and contaminants. [/FONT]
[FONT=Verdana, Arial, Helvetica, sans-serif]RO is the most economical and efficient method for purifying tap water if the system is properly designed for the feed water conditions and the intended use of the product water. RO is also the optimum pretreatment for reagent-grade water polishing systems. [/FONT]

 

Both are pure and can be used to calibrate a refractometer.

 

Well I'll calibrate it again and see if that makes a difference. Another thing to worry about! lol

 

The whole reason for buying a refrectometer is you can't trust hydrometers,right? I would recalibrate the refractometer to make sure it's correct and go with it...put the hydrometer away.

 

Wow. This thread made me put things into perspective. I'm gonna have to order my refractometer soon.
I always use a hydrometer. I have a deep six and an instant ocean and I use both to clarify my readings.

 

Sorry,didn't read all pages of responces before I answered.

 

You'll want to get the calibrating solution, but in the mean time ro water will be fine. It at worst might be off by .001 either way, but it is still better than a hydrometer any day. Those things will give you three different reading off of the same tank all taken within 10 minutes of each other, There just to easy to throw off. Trust the refractometer it is correct. Its just showing how far off you have been up until this point.

 

I liked my living in denial days before I had a refractometer!! haha just kidding.

Thanks for all the help everyone!!