[nige]

La cosa forse nn interesserà più di tanto. Sappiamo tutti che nn c'è un sale migliore...alcuni migliori si però...poi dipende da cosa si vuole allevare, da che metodo di gestione si adotta ecc.

Ma avendo un nanoreef, e pretendendo una certa qualità nel sale da utilizzare, mi sono spinto più in là e ho chiesto in America cosa ne pensassero...dopo una discussione banale senza troppe risposte specifiche ecco cosa esce fuori...


1^PARTE


Original from Reef Central


Nige...this will either help or totally confuse you.

Buyer's guide to marine salt
Matt Clarke looks at some of the many commercial salt mixes on the market and checks out their composition in this special buyer's guide.

Commercial salt mixes make water similar in composition to natural seawater. They’re usually designed to make water of the correct chemistry when mixed with hard, alkaline tapwater. When using demineralised water such as that from a reverse osmosis unit or de-ioniser, certain important elements may be lacking when the salt is mixed.

Unfortunately, high levels of nutrients in UK tapwater make it important to use purified and demineralised water for marine aquaria. If you keep inverts, you may need to add calcium, magnesium and other chemicals to bring the water in line with the composition of natural seawater.
Salts differ not only in what major and trace elements they contain and in what concentrations, but also in the nutrients and impurities.

Research suggests many salt brands do, at times, contain phosphate, nitrate, silicate, and even ammonia and nitrite - although these are often present at very low levels.

Some manufacturers say the presence of such nutrients is due to interference by certain constituents in newly mixed saltwater that lead to false positive results, or pollutants already in the source water.

While this may be the case, tests on prepared seawater using much more sophisticated laboratory equipment reveal similar results.
Research suggests ammonia is sometimes found in freshly prepared seawater. It’s thought to enter the salt as a contaminant in magnesium and calcium chloride. This stresses the importance of testing prepared saltwater before use and of proper mixing, preferably over at least a couple of days.

Some salt mixes are produced using larger quantities of hydrated chemicals than others, so they feel slightly damp to the touch. While this may keep costs down a little, it means they sometimes mix to a high pH (over 9) and may not mix to the correct salinity as some of the salt’s weight is made up by water.
Keep salt in a dry place, preferably in an airtight container.


Cost
Your annual salt bill depends on the salinity of your water, the size of your tank and frequency of water changes. According to our recent reader survey, most of you are running tanks of about 200 l. (44 gal.). Recommendations on water changes vary, but I’ve usually found 25% fortnightly is fine for the average reef tank. This means you’ll need enough salt for about 100 l. of water a month, or a little over 1,200 l. per year. That’s about 42kg, or £100, a year - depending on how you look at it. Buying in bulk where possible works out cheaper.

The tests
Saltwater is complex and we don’t have the facilities (or the chemistry qualifications) to test it with the extreme accuracy required. Sadly, most aquarium test kits are not that accurate.
But we’ve done some basic tests and backed them up by examining results of independent research by Dr Craig Bingman and Dr Marlin Atkinson of the Hawaii Institute of Marine Biology, published in the Journal of Aquariculture and Aquatic Sciences in 1999. Their research compared the chemical
characteristics of a range of aquarium salt mixes to a control sample of natural seawater.

We’ve also sought opinions of readers, and professional hobbyists in the trade.
It’s worth adding that the Hawaiian research paper we’ve used is a little old now and the formulations of some of the salts here may have changed slightly since then. While largely well received and respected by professional aquarists and those whose salts appeared favourably in the analyses, the results have been strongly opposed by other manufacturers.

In our tests, we used purified and demineralised water from a reverse osmosis (RO) unit, so the calcium levels and pH levels we recorded could go a bit higher if you’ve got hard, alkaline water with a high pH. Tests were undertaken using Merck, Tropic Marin and Salifert test kits.


What’s in salt water?
Seawater contains all known elements, so it’s much more than just sodium chloride and water. Some of these elements like calcium, magnesium, chlorine, strontium, potassium, boron, fluorine and sulphur are present in fairly high concentrations, but others - the trace elements - are found in much lower levels.



What’s on the market?

Everyone has different ideas on which salt is best, so you’ll hear conflicting opinions. Most people try a few different ones before settling on one they like.
The results depend on the quality of water you prepare the salt mix with; what works for you might not hold for someone using different water, or who keeps different organisms.
Almost without exception, all of the salts available in the UK are of superb quality; you should get good results from any of them.


Reef Crystals

Reef Crystals from Aquarium Systems contains additional calcium and other elements. This aims to boost levels over that of natural seawater, making it well suited to the reefkeeper who uses RO. It contains a metal detoxifier to neutralise copper that may be present in domestic water supplies, and has added vitamins. It’s claimed to be the fastest dissolving salt, and has a unique crystal structure.

Hawaii Marine Institute’s research: Their research suggested that like the salts on review here, Reef Crystals didn’t produce water of the correct salinity if measured out by weight, being some 6g per litre lower than it should have been.

It came out average in most areas with sodium, magnesium, calcium, calcium carbonate, potassium, strontium, chlorine and sulphur levels all very slightly lower than the levels measured in natural seawater. Only boron was present in greater quantities.

Nutrients were present in greater quantities than in natural seawater, with phosphate levels over 25 times higher, and ammonia levels 39 times higher. The pH of the prepared saltwater was found to be 9.28, the highest measured.
Our tests: We found that the specific gravity was about 1.024 at 25°C and measured the pH at around 8.6. Calcium and magnesium levels were the highest in the test at 446ppm and 1410 ppm respectively.

No ammonia, nitrite or phosphate were detected, but we did find 0.2 ppm of nitrate, a minuscule amount really - and most of the other salts tested positive for this too.

True to its claims, the salt dissolved very quickly, taking just 90 seconds of stirring to dissolve 35g in one litre of water. At the end, however, a few larger particles appeared to have precipitated and were still present in the water.

You say: Reader Simon Orr of Devon was recommended Reef Crystals by a friend and uses it in his reef tank to change about 10% of the water weekly. He rates it very highly for dissolvability, as does reefkeeper Paul Spencer of Hull who appreciates its value for money.