I am very glad that
@duffer included my name in this thread. It did not show up in my search feed, so we were unaware of this particular conversation.
First let me say that Tropic Marin has made NO changes in its formula or raw materials in the past few years. Our products are exactly as they have been. In relation to PO4 levels in the clean water change water made with Tropic Marin salts, the following information is important to know:
Tropic Marin has been manufacturing sea salts for the aquarium hobby, with an almost unchanged formula, since 1964. In the early years of marine aquariums, phosphates were added to sea salts to improve their solubility. By choosing suitable raw materials, this could later be avoided. No phosphate has been added to Tropic Marin sea salts for almost 30 years. (this, by the way, is where the old “no phosphate/no nitrate” labeling comes from. Originally it meant “no added phosphates or nitrates”)
Our sea salts contain natural salts as raw materials, which are purified to pharmaceutical quality. This pharmaceutical purity, of the raw materials, is one of the factors that makes the Tropic Marin sea salts unique. However, phosphate has no maximum parameter limit in pharmaceutical grades of raw materials. For this reason, many pharma grade raw materials have some low level of phosphates in them. Even in these very clean raw materials the level of phosphates may vary from batch to batch depending on the place of mining of the raw material.
So, when natural salts are processed to pharmaceutical quality, traces of phosphate can remain. The raw materials we use come mainly from sites of the dried up “primordial sea”. For this reason, the phosphate concentrations in the pharmaceutically pure raw materials are roughly in the range of the phosphates found in the natural ocean. The Tropic Marin sea salts can therefore contain concentrations in the range of 0.01-0.09 mg / litre of phosphate. Our quality control ensures that raw materials with higher proportions are not used.
In the aquarium, the effect of the phosphate content in our sea salts is small. As an example: if freshly prepared salt water contains e.g. 0.05 mg / litre phosphate, a 10% water change would result in only a 0.005 mg / litre increase in the tank’s phosphate level. Since we now know that all reef tanks need an adequate phosphate level, this could, in the long run, if there is no other phosphate supply, even lead to a phosphate deficiency in the aquarium.
On some Tropic Marin packaging there is still the historical statement "Free of phosphates and nitrates". Since this topic has just recently come to light, we see it as our responsibility to immediately change these statements on the remaining labels and on our homepage. We are currently in the process of changing both our electronic and physical labeling.
The most important thing for every Tropic Marin user, is to know:
We have not changed anything in the proven composition of our salts!