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SneakyPete
01/25/2012, 07:06 PM
So i switched to reef crystals, and apparently, my salinity is way off. I've been having a difficult time with my refractometer and keeping it's calibration. Every time i use it, i have to recalibrate it, but more than that, i have to recalibrate it after testing a couple of times. It's a huge pain in the rump, I need to buy a better one... Anyway, when i switched salt, i didn't get a good reading and have been doing water changes with water at 1.021... This has been probably 20 gallons or so of my volume total and my salinity has been dropped to 1.023!!!

Anyway, I have replaced evap water with salt water (only about 2 gallons thus far) and my salinity has only rasied about 0.0005 or so.

So from what I figure I have about 50 gallons of water, replace about .5 gallons per day of water that is 1.023 (i mixed a rough estimate for evap replacement).

So here is the question for all you mathletes out there: how much water must evap and be added at 1.023 to raise 50 gallons of water from 1.0235 to 1.025?

MuffsAbby
01/25/2012, 07:56 PM
By my calculations, it should require approximately 3.25 gallons. For example, if 3.25 gallons were to evaporate, then (ignoring top-off for a moment), the DT water would increase to approx. 1.0251. That is, you currently have 50g at 1.0235if you subtract 3.25g at 1.000 (since only FW evaporates), and divide by the remaining 46.75g (water remaining after evaporation), you would get to 1.025134:

(50g x 1.0235 3.25g x 1.000)/46.75g = 1.025134

If you then add 3.25g top off at 1.023 to the remaining 46.75g at 1.025134, you should get to 1.025:

(46.75g x 1.025134 + 3.25g x 1.023)/50g = 1.0250

In actual fact, it will require 3.25 gallons plus or minus a bit, depending on the accuracy of your 50 gallon estimate and whether the top off water and your DT water are the same temp.

Sport507
01/25/2012, 08:09 PM
So i switched to reef crystals, and apparently, my salinity is way off. I've been having a difficult time with my refractometer and keeping it's calibration. Every time i use it, i have to recalibrate it, but more than that, i have to recalibrate it after testing a couple of times. It's a huge pain in the rump, I need to buy a better one... Anyway, when i switched salt, i didn't get a good reading and have been doing water changes with water at 1.021... This has been probably 20 gallons or so of my volume total and my salinity has been dropped to 1.023!!!

Anyway, I have replaced evap water with salt water (only about 2 gallons thus far) and my salinity has only rasied about 0.0005 or so.

So from what I figure I have about 50 gallons of water, replace about .5 gallons per day of water that is 1.023 (i mixed a rough estimate for evap replacement).

So here is the question for all you mathletes out there: how much water must evap and be added at 1.023 to raise 50 gallons of water from 1.0235 to 1.025?


Do you have any other point of reference? Like an IO hydrometer?

crankbait
01/25/2012, 08:11 PM
Ok thats some math

SneakyPete
01/25/2012, 08:24 PM
By my calculations, it should require approximately 3.25 gallons. For example, if 3.25 gallons were to evaporate, then (ignoring top-off for a moment), the DT water would increase to approx. 1.0251. That is, you currently have 50g at 1.0235if you subtract 3.25g at 1.000 (since only FW evaporates), and divide by the remaining 46.75g (water remaining after evaporation), you would get to 1.025134:

(50g x 1.0235 3.25g x 1.000)/46.75g = 1.025134

If you then add 3.25g top off at 1.023 to the remaining 46.75g at 1.025134, you should get to 1.025:

(46.75g x 1.025134 + 3.25g x 1.023)/50g = 1.0250

In actual fact, it will require 3.25 gallons plus or minus a bit, depending on the accuracy of your 50 gallon estimate and whether the top off water and your DT water are the same temp.

*clap*clap*clap*

Well done sir. By my rough estimate, i came to the conclusion of a very similar number (i thought it was going to be 3.5gallons)

As to if I have another point of reference, my IO hydrometer reads just a touch over 1.025 right now, so it is about 0.002 over.

Sport507
01/25/2012, 08:25 PM
Ok thats some math

Ok my friend you run the math. Make sure you have something accurate to check the SG. Then come home from work and ato the tank with RODI to the tape mark or what every point of mental reference you my use but SALINITY, IS NOT A MATH PROBLEM. How much did the OP's tank evaporate in a day.

SneakyPete
01/25/2012, 08:51 PM
Sport, i'm not sure why you are so angry, friend. I was asking a question with fixed parameters to get a rough estimate of how much I would need to add and have evap to raise my salinity to a specified ammount. All of it was just to gain a rough estimate, I didn't plan on following it blindly. I'm going to continue to add salt water via top off and check with my refractometer until I hit it, i just know that when i finish this bucket off, i'll be pretty close :-)

sporto0
01/25/2012, 09:06 PM
I think you are misunderstanding Sport, he's not angry, that's just his sarcastic way of being funny. I too have an issue with keeping my refractometer calibrated from day to day, so I use all 3 types to pinpoint my salintity, a glass hydrometer, a swing arm hydrometer (both cheap $8) & my refractometer. BTW, 1.023 is not a terrible # for your salinity, in fact too frequent swings in salinity is worse than keeping at 1.023 & stable.

SneakyPete
01/25/2012, 09:44 PM
I agree 1.023 isn't a terrible number, but what tipped me off was my corals not fully extending. Today's reading was closer to 1.0225. It sure takes a long time to move 50 gallons of water up .002 when you can only add half a gallon per day.

Either way, once I get my tank back to where I want it, I'm going to read it with my swing arm to know where the sweet spot is. At least that thing is always consistant, albeit off a little.

SneakyPete
01/26/2012, 09:00 PM
So i tried measureing my salinity again today. It said it was lower, which is inpossible. Every time I tried the calibration fluid i have, it read either high or low from where I calibrated it at. I think the problem is that my refractometer is a POS and I ordered a new one from BRS. Don't buy a cheap one on ebay, the thing just can't stay calibrated.... I know my tank is pretty good where it is, so I'll leave it be for now and just top off with RODI until it get here. Luckily BRS is based out of Minnesota, so it should be here soon.

Short version: The cheap man pays twice :-(

Sport507
01/26/2012, 10:25 PM
Im sorry I need to apologize to the whole thread more to you SneakyPete. I was short last night but it was a terrible day and that was no one heres fault. Please forgive me for that.

I was way out of line and Sporto0 try to cover for me but I have no excuse and I was wrong. Thanks Sporto0 and yes I can be Sarcastic. LOL

To all that read this thread I apologize to you as well.

Chris27
01/27/2012, 09:01 AM
a glass hydrometer

A very useful tool, often overlooked because it's cheap! A plain ol' floating glass hydrometer is a great tool that one should keep in their maintenance kit, they are usually less then $30 (even some lab grades), last a lifetime, and don't ever need to be re-calibrated if you handle and store them properly.

Meters, refractometers, and swing arms all require some sort of preventative maintenance to keep them up to snuff....they make the reading easier....but it takes some work to keep that reading accurate.

Chris27
01/27/2012, 09:03 AM
Im sorry I need to apologize to the whole thread more to you SneakyPete. I was short last night but it was a terrible day and that was no one heres fault. Please forgive me for that.

I was way out of line and Sporto0 try to cover for me but I have no excuse and I was wrong. Thanks Sporto0 and yes I can be Sarcastic. LOL

To all that read this thread I apologize to you as well.

Apologies are hard, well done my friend, it's folks like you that make forums a better place.

twelvejewelz
01/28/2012, 09:36 PM
I have to recalibrate my refractometer every time i use it as well, and better off it takes 2 seconds to do and id rather know im always on point IMO its normal. I use a couple drops of the pinpoint salinity calibration fluid and its simple and dosnt bother me. For something like this better safe than sorry.