Backyard Aquaponics
A place to discuss aquaponics

Would one concrete building block in my sump tank 250 gal. harm the fish in my fish tank 325 gal? The concrete block would be used to support my sump pump 8 to 10 inches off the floor of the sump to protect my gold fish incase something went wrong.

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It could raise the pH slightly, from what I've read. Somewhere ...

I doubt that will be an issue, but check the pH first and consider adding a little hydrochloric acid or pool acid, to keep that pH down the 6 end of the scale..

PS.. I do wonder about the thought of "protecting the fish" in the FishTank, given that the pump is in the SumpTank.
Ie.. you are reducing the ability to keep water flowing, by that height..
Now.. if you had a lot of critters IN the ST, then you are right.
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If worried about pH use a clay bricks / paver / pipe to prop the pump they are generally pH inert.
Or even weighted plastic like a brad or milk crate.
Rock like granite (but not dolomite) or sandstone should be fine as well.

Concrete and limestone will raise/buffer pH, plus some aspects of concrete are not so good (according to some).


[BuiDoi] Now.. if you had a lot of critters IN the ST, then you are right

I think that is what he is saying - ie. I infer that he has goldfish in the ST.
re: fish = no. The only thing would be solids would settle in the ST floor and you may have to clean manually.
but that is sort of what the ST is for anyway.

Thanks for all the advice. I've been given a double milk crate that will not only raise the pump off the floor of the tank but will also provide a little protection for the small fry in the spring.