Salinity question

[beamer]

Due to very high nitrates and phosphates that are off the chart due to moving a pre existing tank with sand bed, LR,and coral and fish, I am going to do what Eric has suggested and do 20 gl water changes for a week (120gl rr).

My tank water has been running around 1.023 for salinity. After buying a new hydrometer I made new water. The readings were off and I just went with the number that came up most frequently which was 1.022-1.023. After that, My pulsing xenia died and I feared that maybe my salt was actually higher than what my hydrometer had read. I bought a refractometer (money well spent) and my tank water reads 1.026. I bailed some water and put in ro'di. That only got it down to 1.025. I didn't know how quickly I should lower it.

Anyway, I'm ready to do a water change and the water made up is 1.022. My question is: Is it ok for me to add the 1.022 or do I need to increase it to the 1.025 that is currently in the tank?. I thought maybe adding what I have , 1.022, would cause it to average out where it needs to be. Previous owner kept it at 1.023-1.024.

What are your thoughts? I'm open to any suggestions.

Thanks, Cindy

[Randy Holmes-Farley]

FWIW, I would target natural ocean salinity that has a sg of about 1.026-1.027, but that wasn't your question. :D

So you have make up water with a sg of 1.022 and tank water with a salinity of 1.025 and you want to know if it is OK to do15% water changes and not stress things too much?

If that's the question, then I'd say yes. :)

[Randy Holmes-Farley]

Here are some articles on salinity:

What are Natural Reef Salinities and Temperatures…Really…
and Does It Matter?
http://web.archive.org/web/20030218193420/www.animalnetwork.com/fish2/aqfm/1997/nov/features/1/default.asp

Reef Aquarium Water Parameters (a summary general article)
http://www.reefkeeping.com/issues/2004-05/rhf/index.htm

from this one:

"Salinity

There are a variety of different ways to measure and report salinity, including conductivity probes, refractometers, and hydrometers. They typically report values for specific gravity (which is unitless) or salinity (in units of ppt or parts per thousand, roughly corresponding to the number of grams of dry salt in 1 kg of the water), although conductivity (in units of mS/cm, milliSiemens per centimeter) is sometimes used.

Somewhat surprisingly, aquarists do not always use units that naturally follow from their measurement technique (specific gravity for hydrometers, refractive index for refractometers, and conductivity for conductivity probes) but rather use the units interchangeably.

For reference, natural ocean water has a salinity of about 35 ppt, corresponding to a specific gravity of about 1.0264 and a conductivity of 53 mS/cm.

As far as I know, there is little real evidence that keeping a coral reef aquarium at anything other than natural levels is preferable. It appears to be common practice to keep marine fish, and in many cases reef aquaria, at somewhat lower than natural salinity levels. This practice stems, at least in part, from the belief that fish are less stressed at reduced salinity. Substantial misunderstandings also arise among aquarists as to how specific gravity really relates to salinity, especially considering temperature effects.

Ron Shimek has discussed salinity on natural reefs in a previous article. His recommendation, and mine as well, is to maintain salinity at a natural level. If the organisms in the aquarium are from brackish environments with lower salinity, or from the Red Sea with higher salinity, selecting something other than 35 ppt may make good sense. Otherwise, I suggest targeting a salinity of 35 ppt (specific gravity = 1.0264; conductivity = 53 mS/cm)."

another couple:

Reef Aquarium Salinity: Homemade Calibration Standards
http://reefkeeping.com/issues/2004-06/rhf/index.htm

Specific Gravity (and temperature correction of hydrometers)
http://www.advancedaquarist.com/issues/jan2002/chemistry.htm

[beamer]

Thanks Randy,

I had actually read the links, or at least most of them, before that first posting and because of the link I almost didn't post because of what you said about the natural salinity of the sea. I thought maybe I just need to bring the new water (1.022)up to the tank salinity(1.025). I didn't realize the natural salinity was that high.I keep hearing that salinity, temp, and pH have to be exact before doing a water change. However I feel like I really need to get on with the water change and didn't want to do something stupid.

You said in your previous post that I could go ahead and do the water change with the lower salinity, But, if you think I should bring it on up to 1.025-1.026 I will do so and just wait another day before doing so. Powers been off and on here the past few days due to bad weather so I have gotten behind with my water changes.

Thank you for your reply. Thanks for the info. I'm pretty new at this (8 weeks) and my chemistry looks pretty poor and I don't want to loose my livestock. I know the other day you told me that you didn't know that water changes would do that much good with high phosphates, however, until I'm able to change out the sand bed I figure water changes are better than nothing.

I'm open to any other suggestions you or any one else may have.

Cindy

[Randy Holmes-Farley]

The reason that I thought it was OK to do the change is that a 20% change with water at sg = 1.022 to water that is at sg = 1.026 will result in a sg of 1.0252. To drop from sg = 1.026 to sg = 1.0252 doesn't seem very large to me.

[beamer]

Thank you Randy,

I'll get started tomorrow with the water changes. Power's been on and off again tonight. Weather should be better tomorrow.

Cindy

[Randy Holmes-Farley]

That sounds like a good plan. :)