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Subject: Trace Element Testing
>Another newbie Piper Cub here with a question (Actually a 172RG).
Actually, this is a pretty good question.<g>
>Saw the previous posts where it was stated that too much trace element
>could be worse than too little. I have Ph, nitrate, and I could buy a
Actually, you need a general hardness (GH) kit and a carbonate hardness
(KH) or alkalinity test kit. (both, fortunately, are two of the cheaper
How do you test for K, P, Fe++, CO2, etc. ?
IMO, _every_ aquatic gardener who is playing with high light/high growth
systems should have a _low range_ phosphate test kit. These are widely
available, though usually marketed to the reef trade.
Iron test kits are also widely available, although the reliability varies
widely, and is somewhat price dependent. LaMotte and Hach are reliable and
expensive. The Dupla one is much less expensive, but can be a little
difficult to read. Karl Schoeller has a new one out that I like a lot and
is very reasonably priced. I don't know the other brands well, but I know
people have had problems with some of them, so buyer beware.
There _are_ CO2 test kits available, but they tend to give values like "not
enough", "enough" and "too much". You can get just as accurate an idea of
your CO2 concentration by measuring your KH and pH and looking up those
values on the chart that is available in a number of books and in at least
a couple of places on the web. I'm sure it's at the Krib web site, and I'm
pretty sure it is also at George Booth's site.
I have heard that LaMotte now has a K test kit, but from what I've heard,
it's expensive. There is a wider margin of error for potassium than for a
lot of other minerals. And for many people who are using a balanced trace
element supplement, they should be meeting the needs for K in their tanks
Now the question is, do you _HAVE_ to have all these test kits. No.
IMO, You need Nitrate, KH (_mandatory_ if you are supplementing CO2) and pH
if all you keep is low-moderate light, slow growth tanks. If you keep high
light/fast growth tanks, I would add phosphate to the "must have" list,
with iron a close second. GH is important to know, because that tells you
if there are adequate amounts of calcium and magnesium in your water but
you can get that information from the water department, or have it run at
the LFS. Besides it is a cheap test kit if you do decide to get it.
If you want to use the low-tech observer's method of adjusting trace
element supplementation without test kits, here's how to do it. Start out
assuming that you _don't_ need to add macronutrients (NPK) it causes much
more damage much faster to add too much than to run the tank a little lean.
If you are starting with a new tank, do not add any trace element
supplement for the first month. If you are working with an existing tank,
just start now. Find a good, balanced trace element supplement, there are
several out there. If you know someone who uses your particular water
supply, and is happy with a particular product, that's a good place to
start. Dose the tank at 1/2 the rate recommended on the bottle, at the
recommended intervals. Continue this routine for about 1 month.
If the growth has not improved, or it improves, but then hits a plateau
that is still below what you think it should be, increase by 1/4 dose
increments until you see the improvement you want. Sometimes it is hard to
judge this in a tank you see daily, so it can help to take pictures of the
tank on a weekly basis. Even pictures from a disposable "instant" camera
are adequate. Wait a _minimum_ of two weeks between changes of dosage.
You will see changes fastest in fast growing stem plants like Hygros.
When you hit what you feel is the optimum level of dosing, try backing off
by a quarter dose. If the plant growth remains good, this is your final
level. If things start to slow down or yellow, go back up to the higher dose.
If, at any time during this process you experience an increase in algae,
stop dosing completely fro 2-4 weeks, and do an immediate 25-50% water
change. Then resume dosing at the last level _before you experience algae
Now that you have achieved an optimum level of micro nutrient dosing for
your tank, it is time to address macronutrients _ONLY_ if your plants show
signs of deficiency. This is where you really _must_ use a LOW RANGE
nitrate test kit. If, and only if, your tank shows VISIBLE signs of
deficiency, AND there is no measurable nitrate in the tank, your tank _may_
benefit from the addition of nitrate. You can either supplement by using a
low phosphate solid house plant fertilizer inserted into the substrate, or
by adding either potassium nitrate or nitrogen sulphate to the tank. It
may be a good idea to try both, and see which works better, unless you have
a test kit for potassium. Raise the nitrate level no higher than about 5
Over time, you will learn how often you have to add nitrate to keep your
plants happy. Again, stop, and then cut back dosing at the first sign of