Hi all,
Yes, thats right absolutely nothing apart from Co2............By a simple process of elimination we decided that there was nothing wrong with the water change regime, the water was going through a HMA filter and the filtration in the tank was sufficient, the Eheim PlantGro tubes and the Guisemann Aqua Flora Tubes are more than adequate to provide enough quality light for a planted tank. So there was just the final part of the triangle, the nutrients..... Each time I did the water change I tested the Nitrate, Nitrite and Ammonia levels. I always had zero ammonia and zero nitrite levels, but the phosphates and nitrates were always off the scale, so I kept doing the water changes until the tests came up bright yellow instead of dark orange bordering on dark red........Once I got the water to this stage we agreed on doing a trial using half dose only of Tropica Balanced Fertiliser which basically means 25 ml once a week, adding some Sera Mineral salts and some Sera KH plus to buffer the PH and make sure the CO2 was being triggered. Keep the lighting period to 6 hours maximum with only one set of lights on for the first week.
First the normal disclaimer that I've never used added CO2 or EI, and I can't see a time when I ever will, but....
If you have reduced the nutrients down to nothing you can turn off the CO2, mainly because the plant mass won't deplete as much CO2 from the water column as they would when they were in active growth. Although the plants will have stored some excess nutrients within their tissues they won't be able to make use of the extra CO2, mainly because at least one of the mineral nutrients will be limiting growth.
You honestly can't rely on test kits, no-one really knows what they are measuring. Basically if you are a water company with a dedicated lab. and millions of pounds of equipment (ISE, AAS, GLC, HPLC, MS) you can measure a specific set of water parameters accurately. Even bodies like the Environment Agency don't rely on chemical testing (for nitrate you need to use cadmium reduction colorimetry), or portable kit like ion selective electrodes, they look at a combination of Biotic Index and 5 day BOD test to assess the broader category of "water quality".
You can use a TDS meter (so really a conductivity meter) to give you an accurate measure of the total number of ions in solution. If you start with RO you have ~5 microS conductivity (or 3 ppm TDS) and as you add any salts conductivity will rise in a linear manner. Personally I don't routinely measure anything, but I occasionally dip the conductivity meter into the tanks in the lab., and into the rain water that I use for water changes.
Because I keep soft water fish and have hard, but clean, tap water, I can mix together rain, tap and RO water to keep the tanks at about 70 - 120 microS (60 ppm TDS). I choose ~100 microS because it seems to work OK and it is an average value for our rain-water over the year. In the summer the rain water might be ~130 microS and in the winter ~50 microS, which would mean cutting the water with RO or tap respectively. The only time I've ever run out of rain water I just mixed RO and tap to ~100 microS.
It doesn't matter what fertilizer you use, you can use a calculator like the one on Ardjuna's <
"Nature Aquarium" web site>, or <"
James' Planted Tank"> to adjust your nutrients to any level you like. If you really do find a sweet spot measure the conductivity over the week and then use that as indicator. I originally started intending to do this, but soon realized that I'm too shoddy a fish keeper to keep this up successfully for long.
It was at this point that I became aware that I it made more sense to use the health of the plants as a measure of tank health, and that if I used a floating plant it took CO2 availability out of the equation.
If the plants are a healthy green and in relatively slow growth things are fine, if they are yellow and not growing I need to add some nutrients, and if they are deep green, growing well and looking extremely healthy I need to measure the conductivity, and if it is raised, change some more water and look for the reason (dead fish etc).
Once the tank is grown in and the plant mass is fairly large you don't get much algae with this approach, and you definitely don't get rapid algae "outbreaks".
cheers Darrel
