Question on source water

19 years ago

First time poster, short time reader. Hi!

Just starting off on hydroponics and growing hot peppers so it's still a learning experience for me. You'll have to excuse my ignorance. I also want to apologize in advance for the fact that many of my posts might appear rather wordy. It's a problem I have. I want to be as descriptive as possible but I haven't managed to be concise and descriptive at the same time.

On with the question. I'll need to include some background. I currently have a 55gal freshwater planted aquarium. Not wanting to have to tote 5gal jugs back and forth for water changes, I put a 65gal storage tank next to the aquarium for water changes. This allows me to pre-treat the change water, get all the parameters just right and then all I have to do is pump the water from the storage tank into the aquarium and I'm done. I've decided that I could also use this storage tank for my hydroponics refills also. I'm just not sure if the pre-treatment I do for my aquarium is harmful to the hydroponics.

For my planted aquarium, the water needs to meet certain requirements. 2 of them deal with Alkalinity(KH) and General Hardness(GH). The KH and GH for my planted aquarium should ideally be between 7-8 for both KH and GH. EC is not something I'm concerned about as far as the aquarium goes but it naturally changes when I make changes to the KH and GH of the refill water.

Out of the tap, my water has a KH and GH of less than 1(this is considered very soft water with very little buffering capacity. I've tested the EC and it is ~130(this is in microsiemens with equates to something like .13 milisiemens I belive.). In order to raise the alkalinity(KH) of my water, I use baking soda(sodium bicarbonate) to raise it to between 7 or 8. This raise my EC reading to ~420. In order to raise the GH of the water, I use an aquarium product produced by Seachem called Equilibrium. The EC after using the baking soda and Equilibrium is ~720. The components of Equilibrium are as follows:

Soluble Potash(K20) - 23%

Calcium(Ca) - 8.06%

Magnesium(Mg) - 2.41%

Soluble Iron(Fe) - .11%

Soluble Manganese(Mn) - .06%

Derived from: potassium sulfate, calcium sulfate, manganese sulfate, ferric sulfate, magnesium sulfate.

Seachem of course lists Equilibrium as being for aquarium use only.

I currently just have seedling for my hydroponics and I'm using General Hydroponics MaxiGrow nutrient. It says for seedling to use 1/4 tsp for each gallon. Using this amount, the EC of the water goes to ~1200 if I'm using the pre-treated aquarium refill water. I also use Phosphoric Acid to lower the pH of the water to ~6.0.

I'm just wondering if using this pre-treated water is going to be harmful. The Equilibrium adds what I believe to be useful nutrients to the water but I could be wrong. For the most part the peppers appear to be doing okay although the Scotch Bonnet does look a little funny(older leaves are curling upward and look splotchy). The Jamaican Hot Chocolate on the other hand looks great.

I could try to just use the water from the storage tank before it was treated, but I believe that would become difficult once the peppers started growing really well and the need for constant topping off or more frequent nutrient changes started up.

Any insight would be appreciated.

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Comments (3)

tclynx
19 years ago
last modified: 11 years ago
How big a hydroponic system is it?
I used to live in an apartment on city water and the only pre-treatment I did for the hydroponics was to let the water sit exposed to air for a few days to let the clorine out. The water there wasn't too hard and the cf meter read around 3 with just plain water. The ph was between 7 and 7.5. The nutrient tended to bring the ph down some and I sometimes added some ph down but not much.

If the plants are doing well then things are probably ok. If things are looking a little strange, then it might be time to adjust. Keep in mind different types of plants like different things. I found that 1/4 tsp with the GH nutrients was actually perhaps a bit strong (with that water) for tender seedlings and just about the right strength for growing lettuce. I still haven't found the right levels with my new house/well water. The indoor sofened water is way too salty to effectively use with hydro nutrient I think. The outdoor untreated water shows no reading on the EC meter. When I first tested the water outside I though the meter was broken.

Anyway, you would probably have the best luck using untreated but aired water for the hydro. At least you probably don't want the baking soda in the hydro unless you need to adjust the ph up.

Then again, I wonder how your hydro would do using used aquarium water?

Good luck.
jeepidiot
Original Author
19 years ago
last modified: 11 years ago
It's just a self-made flood and drain system that I'm only trying to grow 4 pepper plants in at the moment. Using a 400w metal halide. The resorvoir I fill with 22gal of water.

I'd thought about using the old aquarium water but I figured I didn't know exactly what was in the water after it had been in the aquarium so I didn't want to try and use it and have to try and figure out how much nutrient I should mix with it to get the right proportions.

I use the baking soda to raise the buffering capacity of the water for use in the aquarium. I figure it would also help in the hydroponics to keep the pH from swinging up and down to much. If the nutrients are being used up at a good rate, then the pH would fluctuate a good deal with such lower buffering capacity.

Plants appear to be doing okay for the most part although the older leaves on my Scotch Bonnet have been curling upward and looking kind of splotchy(pale green and dark green). The Tepin has a little bit of upward curl to it also but that's about it. The Jamaican Hot Chocolate shows absolutely no bad signs. I hadn't thought about the nutrient being a bit strong even with the recommended dosage. I just took what was on the label as gospel.

Thanks for the reply. I'm still trying to figure it out. I changed the nutrient and this time didn't add Equilibrium for the general hardness. Going to see if things still work out.
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tclynx
19 years ago
last modified: 11 years ago
Baking soda is sometimes used to raise the pH of water by people who don't want to buy the more $$ pH up. Doing this adds more stuff to the water that you don't necessarily want/need especially if your water already has a pretty high reading to begin with and you are then needing to use a pH down to get into the proper range. I believe the GH nutrients have some small stabilizing capacity. At least they seemed to for me but I guess my water wasn't too hard.

Keep in mind that the recomended dosage is just a starting point. If your water has a really high reading to start with then you might not be able to add as much nutrient as that would make the water just too salty and inhibit nutrient uptake by the plants.