Micro Ingredient

Here are TPN composition

B 0.004%, Cu 0.006%, Fe 0.07%, Mn 0.04%, Mo 0.002%, Zn 0.002%, K 0.80%, Mg 0,39%, S 0.91%

Copper, Zn and Boron are around 300x, Fe and Mn around 50x and Mo around 10x

So, for the same iron dosing as TPN, you'll get 6x more cupper, zinc and boron and 5x less molibdene. I don't know if any of the micro could cause real issues, but I do wonder about cupper for some shrmps and snails maybe. TPN was claimed to be high in cupper compared to other products (it proved to be safe in the long term though), so I don't know if 6x more copper will be still safe. Also, TPN is very low on iron, so usually you have to add it appart to achieve same iron levels as CMS+B for example.

In the end, I don't think you'll have real issues except maybe cupper for some species, and it is even not sure.

I do wonder about another problem: what's the excipient? is it soluble? and what chelate is used? Maybe those are important question to verify before you order

Also keep an eye on some unknown powders that can be fake or contain impurities such as too much heavy metals

 

The copper in it is too high (for me). My locally available traces has just 0.5.
It should be OK if you don't dose over the safe level.

You can read more about safe PPM of copper (well below 0.4 PPM for shrimp) here:
http://www.barrreport.com/inverts/3989-amount-copper-fertilizers-2.html

I think the TPN's percentage already includes water.

 

If you can find Fe-DTPA, then it will be cheaper than Seachem's iron.
Fe-EDDHA can be used too but its purple-brown color is very intense even at
very small dose and the color will not disappear over time, IME.
So Fe-DTPA is a better choice. I'm using Ciba Geigy's Fe-DTPA 7% (around $10.9
per KG which should last nearly 4 years for my current 80 liter tank and the future 300 liter tank).

NPK powder can be faked (or mislabeled). You can prove them with test kits.
But potassium test kit seems to be expensive. So I've only nitrate and phosphate
test kits.

Not sure if a cheap soil test kit can be used to test potassium or not. It's said to detect
potash and I don't know if it also detects potassium.

 

CSM+B can ordered to quiet every country
KNO3, K2HPO4 and K2SO4 can be bought in drugstores. There are many quality samples, from the cheaper to the very expensive depending on the included impurities. If you do 50% weekly WC, then go with cheaper as nothing will build up. Otherwise, could be a good idea to invest in better quality powder, more expensive but less impurities.

There's on the net, don't ask me the link, but google, where the guy tested many powder brands of KNO3 with lab quality tests. He tested many impurities from mercury, lead, zync, cupper, K, boron, Na, Cl, Ca, CO3...

All the tested brands showed some impurities of course, with some brands showing more than others, but nothing to really worry about. I just won't buy any powder over ebay, but only in a drugstore

Sera tests, like most tests should be calibrated. Search the forum for how to calibrate them, there's a thread on it. I find Salifert tests the most precise for the price