Quote:
Originally Posted by RachPreach
so besides testing, how can you tell if the nitrates are too high?
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You cannot, but one contributing factor to Blue Green Algae is very low or zero nitrates. Also, keep in mind that you need to calibrate your nitrate test kit to ensure that it is accurate.
Rex Grigg's site has a step by step on how to do this.
keep in mind that even if your nitrate test kit is accurate, it will be difficult to gauge the precise amount as your nitrate levels will likely fluctuate from day to day depending on how densely planted your tank is, whether you inject c02 or not, whether you dose excel or not, your stocking levels, how much and how often you feed your fish, how much and how frequently you change your water, and what type of plants you have in your tank. Some floating plants can be real nitrate sponges.
As far as dosing ferts in a low light tank that can be tricky, especially if you don't do water changes. With a high light, hight tech c02 tank, you need not worry of any excess buildup of ferts as 50% weekly water changes with something like EI dosing pretty much assures that you will not end up with long term excess buildups that could harm your fish/shrimp. And given that a high tech tank will have c02 injection and high lighting, nutrient uptake by the plants will be higher.
The opposite is true for a low light tank. I dose a pinch/dash of nitrates, potassium, phosphates, nitrates, magnesium and calcium with every water change. But then I do weekly water changes on my low tech tanks and they are undestocked. Plus I dose excel daily and double with every water change which pretty well gives me some more wiggle room by allowing more ferts to be used up by plants.
I would suggest treading very carefully if you decide to dose ferts on a low light, lightly(even heavily) planted low tech, non-c02 tank where you plan to fully stock the tank and not do water changes for weeks on in. Personally if I planned on setting up a fully stocked low tech, low light tank, with minimal water changes, and feeding of fish frequently, I would dose based on any observations or indications of possible nutrient deficiencies, such as yellowing of leaves, otherwise, I would not dose any ferts.