water report

[boggie]

hi everyone,
please could somebody have a look at the following water results from my local water comp and tell me if they need tweaking for a planted tank with co2 injected.
AMMONIUM (MG/L NH4) 0.010
CARBON ORGANIC TOTAL0.844
CONDUCTIVITY (US/CM)139.079
NITRATE (MG/L NO3)1.598
NITRITE (MG/L NO2)0.003
PH7.913 .
PHOSPHORUS (UG/L) 580.130
SULPHATE (MG/L)21.263 .
TOTAL IRON (UG/L)22.620
TOTAL MANGANESE (UG/L)3.570
TOTAL SODIUM (MG/L)4.125
the local ph is more like 8.4 and the kh is 0-2 degree and gh is up to 5 degree. I dont know if the jump from 8.4 ph down to tank water level of 6 ph is going to upset things. I do large water changes 50% twice a week, because of a lot of water yellowing bogwood. I am thinking of fert dosage in the future.
there was a lot more results to the water test, but most of them were things i ve never heared of. no potassium result.

 

[dw1305]

Hi all,

please could somebody have a look at the following water results from my local water comp and tell me if they need tweaking for a planted tank with co2 injected.

Yes, it will need a bit of tweaking. Basically, it is very low in everything, and if the water company hadn't added NaOH to raise the pH it would be pretty close to being RO straight out of the tap. It presumably comes from a reservoir somewhere in hills, where there is high rain-fall and acid rocks, like the Elan valley etc.

The pH is a bit of a red herring, it has been raised by the addition of the OH- ions (alkalis are H+ acceptors or OH- donors), but you don't have any buffering. All the alkalinity is in solution as OH- ions, pH is a measure of the H+:OH- ion ratio, but doesn't tell us anything else. As soon as the amount of H+ ions rises (acids are H+ ion donors), the pH will fall, potentially to very low levels. The acid addition from the small proportion of CO2 that goes into solution (as carbonic acid H2CO3) could be enough to cause the pH to fall very quickly to a very low level. This isn't necessarily a problem to your fish or plants, and I don't actually believe in the "pH crash" scenario, the problem is the with the measurement of the pH, not the actual acidity of the solution. In very soft water the pH can veer from pH4 to pH8 to pH4 during a 24 hour cycle, entirely dependent upon the relative balance of CO2 & O2 in the water.

Because of this instability most people buffer up there water to 3 or 4 dKH/dGH using a mix of potassium bicarbonate (KHCO2) and magnesium sulphate (MgSO4.7H2O) etc. This makes management of biological filtration easier. There are plants that you can grow in very acid, nutrient poor water (Blyxa, Tonina, Eriocaulon etc.), but the range is increased in slightly harder water.

Have a look at James' Planted Tank <http://www.theplantedtank.co.uk/index.htm>, he has a useful calculator for the amount of compound needed to raise dKH, as well as a calculator for fertiliser addition.

Water hardness: <http://www.theplantedtank.co.uk/water.htm>
Dosing calculator: <http://www.theplantedtank.co.uk/calculator.htm>

cheers Darrel

 

[boggie]

Thanks Darrel .I am going to read up your sugestions . I didnt know about the NaOh being added, the water comp should have said in the report. i m in brynithel,wales so you also got the living in the hills with heavy rainfall bit right!
thanks Andy