Dear Kenneth,

The evaporation of sea water samples at a temperature from 20 °to 35 ° C with large amount of alcohol started from the least soluble salts — the carbonates of calcium and magnesium and calcium sulfate. Then fall out more soluble sulfates of sodium and magnesium, chlorides of sodium, potassium and magnesium, and the sulphates of potassium and magnesium. The sequence of crystallization of salts and the composition of the sediment can vary depending on temperature, rate of evaporation and other conditions. Anyway for my opinion better to use 70% alcohol for fixation of marine samples. To dilute crystalls put several drops of acetic acid.

Andrey

Kenneth,

It may also be better to fix your samples first in 95% EtOH and then store them in 70% EtOH. Make sure you have appropriate storage vials for this as well.

Tom

Hi Kenneth,

If for DNA conservation, only use 95% final conc. I guess you want to preserve larger things, copepods and such? You can sieve it and rinse the sieve out with 50% EtOH. That should get rid of most of the problems. 

For most of our routine work (microscopy), we tend to stick with acidified Lugols.

Good luck, 

René

Hi Kenneth,

I have a book and describe the technic:

Distributional atlas of fish larvae of the southern region of the Gulf of California (February-March 2005)

R. Avendaño Ibarra · R. De Silva-Dávila · G. Aceves-Medina et al. (2009). In spanish

Follow the suggest for DNA conservation.

Ray

thanks everybody for your reply. Someone else suggested using saline ethanol... Perhaps we'll try that. 

All the best,

Kenneth

You can also filter your seawater plankton (preserved with 95% ethanol) , gently flush through with fresh water and represerve in fresh water with 70% ethanol