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Plants, Hardwater, Amonia, Nitrates, and cycling

Posted by greenthumbdewd Ohio (My Page) on
Mon, Aug 25, 08 at 12:37

Its been along time since I've had an aquarium. It seemed like every time I tried having one, my fish always ended up dying on me. I attribute that to my ignorance on proper maintenance.

Recently I learned about aquaponics (a form of hydroponics) and how tank water can be used as a nutrient source to grow plants. I read that when an aquarium is used to grow plants the fish tend to be healthier.

I will be keeping a grow tray above the thank and water will be constantly pumped through the tray and fed back into the aquarium. Since gardening is a love of mine I figure I would give having an aquarium another run. I don't know how many people here would have the experience to answer these questions, but its worth a shot!

Hard water - I live in a hard water area. How bad is hard water to fish? As plants take in the nutrients, will they absorb the minerals in the water and soften it? It seems like it should since plants use minerals, but I'm not sure if the minerals in hard water are in a form plants can absorb. If the minerals in hard water are not usable to my plants, what can I use that is non toxic to humans to soften the water? I read baking soda is a good alternative? How can I use baking soda in a 20 gallon tank?

Ammonia and Nitrates - These are nutrients plants use for green growth. I'm starting with green leafy vegetables like lettuce (light feeder) and spinach (a heavy feeder). Lettuce likes its liquid nutrient source to be around 560-840 ppm and spinach likes 1260-1610ppm. With that said, and providing there is enough plants in the tray, I shouldn't have to worry about ammonia and nitrate levels right?

Cycling - With the plants there to absorb nitrates and possibly ammonia, do I still need to worry about cycling the tank, or is cycling still necessary, but speeds up the process?

Partial water changes and gravel siphoning - Will I still need to do weekly partial water changes? Will a monthly siphoning of the gravel still be a necessary chore, or does that depend on filtration and how clean the fish like its water to be?

Follow-Up Postings:

RE: Plants, Hardwater, Amonia, Nitrates, and cycling

Well, you have a lot of questions there. Ill try to get some of them.
First off, I have a 20g planted aquarium. I have a small hang on filter, NO air, a DIY CO2 injection. I change my water about every 4-8 weeks and do 1/4 of my water, five gallons. I have a gravel substrate with fertilizer tabs in it topped off with sand.
I stated that so you can see what direction Im coming from.

Now how are you setting this up? Do you take the water out and water a garden? Do you have planters above the tank and the roots grow into the tank? Are you speaking of aquatic plants and the plants are submurged in the tank?

I have soft water, I have a RO set up for my well water on my sink. That water is just about pure. I add salt to it and 'flourish' brand micro nutrients to make the water like river water with out the toxins (no motor oil in my water, bad joke, I know). I add 1/4 tsp of epsom salt to increase hardness and 1/4 tsp baking soda to increse pH because of the CO2 injection. With that the pH ends up 7 and the hardness is still soft.
In the past I had my tank at another house where I only had tap water that was medium hardness. All the plants grew the same.
Unless you are growing aquatic plants, I would not worie about the hardness. There are some difficult aquatic plants that need soft water but I can not think of any earth rooted plants that need soft water. I have a bunch of bonsai and potted plants and sometimes I use the aquarium water but for the most part they get hose water. Im drifting away from the topic. Let us know how you have this set up. I hope my rambling was helpful.

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