Hard Water Planted Tank

[steadyb]

Hi,

Ive just started a planted tank and i am 3 weeks in. I have hard water @ GH16, KH 11, ph7.7, and use CO2 fert. What is causing me bother is the fact that i can add and add CO2 but the pH and KH don’t change. I cannot test for co2 and have to rely on these kh and ph readings.
Algae is on its way and i am loathed at what might happen. Is there a chance that surface agitation or the fact that the tetramin co2 system (membrane system) was by the filter and pump might have something to do with it.
Should i be expecting small amounts of green algae in the intial stages?
Ferts are esha cryptoplus, prophyll and nutrafin keeping NO3 to approx 30ppm
Tank is juwel record 90 with 3x 20W bulbs

Any thoughts are much appriecated

 

[RadaR]

Firstly, you cannot rely on the pH and KH relationship to work out CO2. That rule only works if the only acidic compound in the water is carbonic acid. It is very unlikely that this is the case, therefore you have to use other methods of reading CO2 concentration. The best that we know of so far is the drop checker method. Obtain a drop checker (see Aquaessentials.co.uk) and you will also need the 4dk solution. You add a certain amount of the 4dk solution to the drop checker and 3 or so drops of bromo blue (it's liquid for the lower range pH liquid test from API, or the Hagen test kit). Carefully stick to the side of the aquarium being careful not to spill the contents and after a few hours you should have 1 of a possible 3 colours. Blue means the CO2 is too low. Yellow and the CO2 is too high. Green means your spot on. There should be a link to all of this that is explained a lot better. I'm sure someone can find it, hint hint.
The Tetra CO2 system is inadequate to do the job. In fact it's really quite poor. You'd be better off with a twin set of fermentation units generating CO2 that then lead to a small glass ceramic diffuser. This is often referred to as DIY Yeast CO2.
Until you get CO2 sorted, only have one of your lights on. Either yes, you will have an algae farm soon.