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Phosphate & Water Reports and seachem nitrate test kit
My parents local water report (London, UK) gives a reading phosphorus min;
mean ; max (1104;1104;1104 ug/l) and orthophosphates (832;832;832 ug/l).
Andy, do you have any figures on orthophosphates?. I am not sure how these
two readings relate to each other, but these levels of phosphate are quite
high.
I looked in the archive and found a post in February by Tim Mullins that
suggested that his tanks had become phosphate limited. He was adding 1 ml
monopotasium phosphate (to raise water column concentration by 0.02ppm)
occasionally.
It would be helpful to hear from Tim to determine how much phosphate his
plants are using over a period of time, and what concentration the
phosphates can be maintained at without an algae outbreak. I understand
that he uses heating cables and laterite, this may mean any phosphate
additions are 'filtered' out of the water column and into the substrate
(where only higher plants can utilize it).
Andy, the recommended value for phosphates (according to Sears and Conlin's
experiments and observations) is no more than .1 ppm. How much water do
you change in your tanks?. If the answer is 10% a week then (assuming no
phosphates already in the tank) you will have an immediate concentration of
.14 ppm phosphate. At this point you should be experiencing problems with
algae. Have you experienced any algae, if so which variety?. If you
haven't experience problems then something must give, either you water
report is incorrect, the phosphate limiting method of algae control needs
amendment or my calculator is in for a beating.
If you are experiencing algae problems; many Listers recommend phosguard or
phos-zorb to solve phosphate problems - either placed in the tank filter or
used to pre-filter tap water (does anyone know how quickly these phosphate
extractors work i.e. can you run tap water through them and expect 0
phosphates to come out the other end?).
What does the water report give the nitrates as?.
On the subject of nitrates, what do people have to say about the seachem
nitrate test kit?. I have found it to be difficult to read and inaccurate
according to their own validation solution.
David Brooks