[Surf]

low cost test kit can only take you so far in monitoring nutrients. Escpacially for the micros There are a few iron test kit. and maybe some copper test kits but that is about it. And some of those are only designed to detect concentrations near the EPA allowed upper limit. They may not work well at the target concentrations typically used in planted tanks.

The best way I have found to measure nutrients is the ICP-OES lab test. You send a water sample in and it will measure all nutrients except nitrogen down to a concentration of 0.001ppm (2 part per billion)d. Triton labs in europe has been doing this for salt water leef aquariums. IN the US I have used ICP-Analysis.com:

https://www.amazon.com/ICP-Analysis-Elemental-Water-Test/dp/B071HVPBVD/ref=sxts_sxwds-bia?
crid=2B2TOCME39Z2C&cv_ct_cx=icp+analysis&keywords=icp+analysis&pd_rd_i=B071HVPBVD&pd_rd_r=e01d4ada-527c-4089-b7dc-3d8371494f82&pd_rd_w=83teT&pd_rd_wg=50ylo&pf_rd_p=1cb3f32a-ccfd-479b-8a13-b22f56c942c6&pf_rd_r=E61TBE7WZXMR2X326GA4&psc=1&qid=1578110540&sprefix=icp-analysis%2Caps%2C216

iT costs $30 and you get the results in a week.

If any plant nutrient has a zero in the test result you have a nutrient deficiency. I first used it when I had a nutrient deficiency I couldn't fix. The test showed I had two deficiecies in my RO water tank. CL and Manganese were zero. I don't know why it happened but the tank was back to normal in a week.
w
one other option for testing are hanna instruments checkers. Each checker detects one nutrient and cost $50. It is an electronic device that anaalies the color and gives you a digital readout. You cannot get a checker for all nutrients but the phosphate, ammonia, alkalinity and iron checkers are very good. They don't have a nitrogen checker. Be advised they sell salt water and fresh water specific checkers in multiple ranges so before ordering one verify the range is what you need and that it is a fresh water meter.

 

[Surf]

Although I registered on this forum a while ago, I have returned to it very recently. I was drawn to your question quite simply because you take an interest in actually measuring nutrient levels. So do I. But, I'm still trying to determine what we should be aiming for with each nutrient.

There is a new trend in planted aquarium. Some people are now making their micro fertilizer as well as the macro NPK dosing. The reason for this is that the most popular purchased micro fertilizers didn't work well for everyone. Many purchased fertilizers idon'thave all nutrients plants or they simply don't have enough of another nutrient. Some people may have nutrient rich water while other have soft rain water and others may be forced to use pure RO water. Some tanks may have nutrient rich soil substrates while others have a nutrient poor substrate. Some tanks have a lot of fish and a lot of nutrient rich fish waist while other tanks may have few fish. No fertilizer or fertilizer recipe is going to work equally well in all types of tanks.

You can use this thread to compare your tank to what others are using. And unlike many other threads it covers all nutrients plants need.
https://www.plantedtank.net/forums/11-fertilizers-water-parameters/1288329-share-your-dosing-thread-31.html

This thread is more about why people are making there own micro and how they do it.
https://www.plantedtank.net/forums/11-fertilizers-water-parameters/1221018-custom-micro-mix-thread.html

testing is helpful to :

1 catch a hazardous condition before it kills your fish.

2 Detect nutrient deficiency. If you are just missing one of the 14 nutrients a plant needs to grow you could end up with a lot of algae and dying plants.

3 to detect a high excesss level in a nutrient that might be harm your plants and fish.

4 Monitor nutrient consumption of your plants and adjust the dosing levels to optimize the overall health of the tank. this is refers to by some as "dial in my nutrient levels"


for a new tank problems are more likely to occur so you will probably do more testing. However as you work through the problems the need for testing should diminish.