# Preventing stagnant water under artificial rocks



## NotThePainter (Oct 28, 2013)

I'm building a 75 gallon (4 foot) Mbuna tank and I'm using artificial rocks from universalrocks.com. (My bad back pretty much eliminates any chance of using real rocks even though I would like to.)

I have lots of small ones and two large ones. These rocks are hollow and I'm worried about the large ones getting stagnant water inside them. (And other thread on these forums alluded to that issue.) That person drilled holes in his and used the under gravel filter to circulate water. I don't have one of those.

I do not want to put air stones in them, nor do I think power heads in them is a good solution, primarily because you would probaby not know if the powerhead ever failed.

I loathe to cut big holes in them to make caves, that looks so wrong to me. I'm coming up blank here. Any ideas?


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## CjCichlid (Sep 14, 2005)

So people have had problems with this before?

The simplest solution I see is to move/lift up the rocks regularly, say every water change. Other than that, the only thing I can think of is to drill some holes in the rocks small enough so fish can not get into them.. Or silicone them in place?


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## NotThePainter (Oct 28, 2013)

CjCichlid said:


> So people have had problems with this before?
> 
> The simplest solution I see is to move/lift up the rocks regularly, say every water change. Other than that, the only thing I can think of is to drill some holes in the rocks small enough so fish can not get into them.. Or silicone them in place?


I worry then about fry getting in, squeezing in, and then being able to get out, dying etc...


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## chmey (Apr 29, 2010)

Go to the dollar store and buy the cheapest turkey baster you can find. 
A few underwater squirts every day or so will keep the area clean and substrate stirred up.


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## spotmonster (Nov 23, 2006)

NotThePainter said:


> These rocks are hollow and I'm worried about the large ones getting stagnant water inside them. (And other thread on these forums alluded to that issue.)


Unless sitting in an aquarium with zero water flow of any kind, In my opinion, this is a total non issue. Click on my 90 gallon tank thread in my signature and you will see a tank that has been set up for years and contains a ton of both real and fake rocks. The fake ones have holes in them and the fish can swim in and out. I have not had any "stagnant" issues nor believe I ever will.

Besides cleaning underneath them every once in awhile as Cj suggested, don't worry about that. :thumb:


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## NotThePainter (Oct 28, 2013)

Awesome, I'll worry less and get back to my build. Hopefully I'll have fish soon. I just need to get the background in place, spent 2 hours on it last night...

I'll be doing the fishless cycle but doing it with establish media from one of my other tanks, I'll just take the top ceramic tray of the Eheim out and put the media in the filter part of the sump. Hopefully the cycle will be fast.


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## ozman (Sep 7, 2012)

CjCichlid said:


> So people have had problems with this before?
> 
> The simplest solution I see is to move/lift up the rocks regularly, say every water change. Other than that, the only thing I can think of is to drill some holes in the rocks small enough so fish can not get into them.. Or silicone them in place?


i could not agree more. i too have a few universal rocks. i will be lifting with each weekly water change, best way inmo. if you cilicone then you may wish to change your tank later for a new look...so i would not do that.


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## CrypticLifeStyle (Dec 14, 2009)

Option of just putting the stone right on the glass, then put sand around it? Other then that i would agree not to worry about it.


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## cichlid-gal (Apr 27, 2012)

I am not familiar with the universal rocks or how they are manufactured. I am familiar with things like fake holey rock and fake caves (I had these in my tank when I first started out) which have areas in them that can "trap" air even though there are some small holes in the tops of the decorations. The problem comes in more from trapped air than water. If you get an airpocket in the open space things can go bad in there and when you do find it...yuck.

And no, I did not move those decorations a lot because I did not know to do that and even if I did, I'm not sure I would have. Admittedly lazy that way. Now, I only use real rock and real wood with no holes for things like that to happen.


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