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Re: Iron, Copper, K2SO4, Chlorine, GH

Caleb has some questions....
"...Therefore, there may be a better (or additional) guide
for the OTHER trace nutrients.  One example may be to test/dose for Copper,
and keep it BELOW a certain level.  Does this make sense when dosing a trace

That would depend entirely on which trace element mix you are using, and how
much Copper there is in it - if you look at the component lists for 10
different trace element mixes, you will probably find 10 different sets of
numbers - they can vary quite a bit.

You _might_ want to look at the chart on Philip Barak's site
(http://www.soils.wisc.edu/~barak/soilscience326/macronut.htm). It gives
concentrations, in kg/L of each of the various macro and micro nutrients
deemed _sufficient_ for typical plant growth. I would imagine that the
ratios of each of the micronutrients, one to another, might be able to guide
you  when tying to pick a micronutrient mix (i.e.are the ratios in the mix
similar to what plants actually need, or is anything present either in gross
excess or deficient in any one - or more - element?)

Also, how much of any fertilizer you add to your tank is going to depend
greatly on how much light it gets and the number and species mix of the
plants you grow. Each tank is going to be different and you should base your
dosing in _your_ tank on the results that you see there. Dosing info from
someone else's tank might be totally inappropriate for your conditions.

If you see someone else's tank, and it appears to be doing noticeably better
than yours, or if any particular plants in it are growing better there than
the same species grow in your tanks, then you might want to adjust your own
regeime, gradually over a period of several weeks (either more or less of
some or all nutrients, always keeping an eye out for balance). Learn to
depend upon your plants and your eyes - for our purposes, they are much more
reliable than test kits. I know that it takes time, but its a skill worth

"I also find I do not need any K2SO4
to keep Potassium at 20-30ppm.  If I add it, I get to 40ppm.  Is there any
reason to add K2SO4 if the KN03 seems to provide sufficient Potassium?  My
plant growth is fairly high, plants are quite green, and no algae (yea!)."

In addition to Potassium, the K2SO4 is also a potential source of Sulfur,
another important macronutrient. But Sulfur is also in (MgSO4 + 7H2O). Also,
depending upon how much Sulphur is in your water supply naturally, and how
much is added via fish food, you may not need the K2SO4. Have you tried it
both ways - with and without the K2SO4 and looked at how your plants react
(as opposed to spending so much time with test kits?)

If your plants are growing well, and you don't have problems with algae,
perhaps you don't need to worry

"In a 29g heavily planted CO2, etc tank, at what quantity should tap
water be de-chlorinated (I use Amquel), e.g. if I top-off evaporation, by
adding a gallon or two of tap water, should I be concerned?"

That would depend upon whether or not the water contains only chlorine or if
it contains chloramine (chlorine+ammonia), and how much of either is there.
Water utilities can change the amount of disinfectant they add to the water,
depending upon the time of year. You can easily work out how much will be in
your tank after a water change if you know the tank volume, the percentage
you change and the concentration of chlorine in your tapwater. If you are
worried, add the recommended doseage of a de-chlorinator. Chlorine will
leave the water by itself after about 24 hours, so if there is only a tiny
amount present I wouldn't worry about it, but Chloramine can persist for a
lot longer and you never know when the level in your source water might
suddently spike upwards.

"Also should I focus in levels of "Free Available
Chlorine", "Total Residual Chlorine", or Combined Chlorine"?"

IMO, that is _way_ too much information. Find out how much
Chlorine/Chloramine your water utility adds to your tap water and treat the
water you change in your aquarium appropriately. I don't think you need to
worry about the species of Chlorine that is in your water (or not)

"What is the significance of Ca2+ vs
Mg2+?  My tank reads Total=95ppm (just under 6dGH), Ca2+=60, Mg2+=35."

That gives you a 2:1 ratio of Ca to Mg, which is fine. Natural waters can
easily vary from 1:1 to 4:1 without much of a problem - for many of their
functions within plants Ca and Mg can almost be considered interchangeable.
I wouldn't worry about changing the ratio, especially since you say that
your plants are growing well.

James Purchase