# cement/concrete?



## rnocera

I've been reading a lot of stuff about people using cement or concrete to make different decorations in their aquariums, and I've come up with a question about it-
pH. Every DIY instruction set says that after curing, the pH will return to normal. However, all of the aquariums that I've seen that contain cement are either cichlid tanks, or saltwater. Cichlid tanks normally start out with higher pH, and saltwaters often have higher pH as well, because of the minerals & such in the water, correct?

So, what happens if you use cement in a normal freshwater aquarium, with a normal, or low pH? After curing, does the pH drop to "normal", or is it perpetually raised, due to lime leeching out of the cement into the water?

Common sense says that eventually, it would cure, and be fine. After all, lots of fisheries use cement enclosures, and the big aquariums (like, Pittsburgh PPG Aquarium, and L'Aquarium in Barcelona) use cement in their enclosures. Tons of man-made reservoirs & lakes use cement to line them, and make dams. But, do they maybe use something special? I've seen some things that say you should use special stuff, and other things that say you don't need to use special stuff, that regular portland cement works.


----------



## confuted

Part of it will be a function of surface area of cement vs volume of water. If you have a ton of water, a little bit of cement isn't going to affect it much (especially once it's cured), but if you have the opposite, and have a ton of cement and only a little water, you might see problems. Keep in mind that cement takes a very long time to cure. Technically, it takes several hundred years, but several months to a year would probably be enough time for it to be cured enough. Cement will continue to cure even under water.


----------



## LS6 Tommy

IIRC, cement leaches Lye = dead tank occupants. I have benn wrong before and no doubt will be again.

Tommy


----------



## essabee

rnocera said:


> SNIP
> Common sense says that eventually, it would cure, and be fine. After all, lots of fisheries use cement enclosures, and the big aquariums (like, Pittsburgh PPG Aquarium, and L'Aquarium in Barcelona) use cement in their enclosures. Tons of man-made reservoirs & lakes use cement to line them, and make dams. But, do they maybe use something special? I've seen some things that say you should use special stuff, and other things that say you don't need to use special stuff, that regular portland cement works.


I don't know about others, but I do use several types of cement, depending upon what I am building and where.:icon_roll 

Then even when you are building anything for a small softwater aquarium, you can still use normal portland cement, provided you give a reasonable time to cure (about a couple of weeks), then dry it and cover it completely with a coat of aquarium safe silicone. 

You could even stick coloured gravel or sand (aquarium safe ofcourse) to the silicone for texure or colour effects, and you then need not worry:fish1: .


----------



## Aquamanx

You could use a "water potable coating" like Sika Topseal 107. It's been used for years... If you are looking into it to build a background for a tank take a look at this background!.
Hope this helps!
Steve X.


----------



## trackhazard

The reef guys use cement to make their own base rock. Don't see why their curing methods wouldn't work for a FW tank unless there is something inherent to saltwater that makes this method safer.

Reef Central Online Community - The Ultimate DIY Rocks!

-Charlie


----------



## vraghu

I have 2 Nos of 6 x 2 x 2 Ft Cement Tanks , which i made for experimentation purpose, i never had any issue with it so far, it located outside my house with plenty of sunlight,, no issues, plants and Fish thrive in it ..

After building the Tank i left it full of water for 1 to 1 1/2 months to cure and leaching , i used to change 50% water at these times , after that , no issues so far...

rags


----------



## mistergreen

what about cement ponds?
any issues there?


----------

