Is concrete in my watering tank a bad idea?

I'm building a stacked plant tower (usually used for strawberries) and my plan is to start with a barrel of water and a pole in the center to hold/align the stackable planters above it and pump water to the top container to water the plants. The water will then filter through each layer and any leftover water will find it's way back into the barrel at the bottom. My thought is to cast a concrete base to hold the center pole to support the containers and keep it all from tipping over. This concrete base would sit inside the water in the barrel. My concern is whether there may be a danger of chemicals leaching out of the concrete into the water and thereby into my veggies and herbs that will be planted in said containers. I understand that some lime will leach out but I'm not sure if that is something to be worried about or if any other chemicals may be an issue as well. Does anyone have any experience with this sort of thing?
Thanks in advance for your time and any input you may be able to offer.
Flint

That is a good idea for a planter! I like it!

New cement is alkaline and leaches lime for a few months (depending on conditions), as you've mentioned- some plants will not like this. Concrete is sometimes made including recycled components such as fly ash or industrial slag- which could contain and leach nasties, but if you're making and casting the concrete yourself you will know what you'll be putting into it. Ensure the concrete you buy doesn't include ash (manufacturers should know) and put clean aggregates in.

Thanks Charli - I was planning on just using a bag of quick mix in a 5 gallon bucket. I wonder how much it might help if I leave the quickcrete in the bucket to reduce the amount of surface area of concrete that contacts the water. Another thought is that since the plants will be in a soil mix that is high in peat moss (acidic) then perhaps the alkalinity added by the crete won't be so bad..... hmmmmm.
I do have a nice PH testing kit so I think I will keep tabs on the PH of the water for the first season or two just to be sure. I was primarily concerned with other possible contaminants that concrete might add to the water but so far my research has mostly shown the lime as the only thing people have mentioned here and at other sites.

Once I have it set up and running I'll try to grab a picture of it and post back here as to how things are working out with in - just in case someone else somewhere else might have the same idea.