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Re: Water Test results

On Fri, 17 Dec 1999, Jamie Noble wrote:

> Question # 1:
> I've searched the Krib for an article listing recommended optimal KH/GH
> values but so far without luck (I know this would vary according to plant
> types but at least a minimum/maximum range would be nice). Any thoughts on
> these values above?

There's nothing wrong with the KH and GH in your water.  You probably
don't want less than 2 degrees of general hardness in a planted tank.
General hardness is a measure of calcium and magnesium concentrations.
Both calcium and magnesium are essential plant nutrients; your plants need
them and the hardness they create.  Buffering capacity (KH) is very
important if you inject CO2.  If you inject CO2 you will probably want 3
or 4 degrees KH.  Even if you don't inject CO2 you will probably want to
keep at least 2 degrees of alkalinity to help keep the pH in your tank
from drifting downward between water changes.

I don't think there is a well-defined maximum for KH or GH.  They can be
so high that the water becomes brackish, and even then some plants will do

> Question # 2:
> I understand that the limiting factor in a tank can often stop plant growth.
> I am quite surprised to see 0 Nitrate and 0 phosphate. Thoughts? I think the
> plants are probably eating Ammonia rather then producing Nitrate but the
> lack of Phosphate is a surprise.

I don't know how sensitive your test kits are - what the lowest possible
measurement might be.  If a zero reading implies (for instance) that
nitrate is less than 1 mg/l or phosphate is less than 0.05 mg/l then
certainly the algae and floating plants in your tank aren't well
nourished.  If instead it means that nitrate is less than 10 mg/l and
phosphate is less than 0.2 mg/l, then the algae and floating plants may
have a great nutrient supply.  The rooted plants have access to nitrogen
and phosphorus in your substrate, so your measurements don't necessarily
mean that the plants will be limited by low nitrogen or phosphorus.

The general hardness of your water may help keep phosphates low.

> Question # 3:
> Whatever I should have asked but didn't.

Your low nutrient concentrations aren't necessarily a problem now -
possibly growth in your tank is limited by CO2 availability.  Your CO2
system will change all that.  Once you have the CO2 system working you may
need to increase the dosage of TMG and either feed your fish more or
fertilize your tank with macronutrients.

Roger Miller