View Full Version : Weathered Flagstone

04-15-2003, 02:46 PM
Just wondered if any body uses it, or knows someone who uses it.

They put it in ponds, so it should be safe for the fish.

I'm just wondering. I asked at the lfs where I get my lace rock and they said it should be ok. I just feel better if I know that someone else out there uses it.

Thanks in advance for your input. :)

04-16-2003, 03:31 PM
Hi Merlyn,

Yes totally safe, it is nothing more than slate. Totally inert.

Regards, as always


04-16-2003, 04:13 PM
Thanks Matt! Good thing, because I bought 230 lbs of it to put in my 55g Tang tank! :rolleyes:

I can always count on you to reply to my questions! :D

I asked at the landscape place, but I don't trust them. :nervous: They're not fish people.


04-17-2003, 09:41 AM
You are a brave person! Seriously! 230 pounds in a 55 gallon tank... I cant bring myself to do that. First off my fish dig under the rock I have for them and the rock is always tumbling around because of it. Secondly, I look at that quarter-inch of glass and just say, "there is no way that can hold any significant weight".

Is there anything that you do to add extra support to your tanks before you add that kind of rock weight, or do you just add it and pray that the tank's bottom glass will hold up?

This has been troubling me for a while now...


04-17-2003, 03:46 PM
:eek: 230 lbs in a 55 wow!!!

How are you going to keep your substrate clean with all the rock work?



04-17-2003, 09:28 PM
Pain in the a**, but once a month I dismantle the rock structures in BOTH tanks and clean gravel. I've just gotten used to doing it.:rolleyes:

As for the weight, I contacted Perfecto for weight limits for rocks/decorations and there are no limits. They simply suggest you use "egg crate" under the gravel. They also suggested that I further support the tank by putting plywood under it, which had been done when I first set it up...remember Matt? The metal stand problems not too long ago?:(

When I put the rocks in, I won't have that pieces stacked so they can fall, and I will have clay pots in there, too. This will help to make more caves and keep them from digging all the rocks up and knocking them into the glass.

If it floods the living room floor fOx.:wink: I'll let you know immediately! (I like to live dangerously, could you tell?)

04-18-2003, 06:56 AM
As far as the weight goes... keep in mind that even in an empry 55, the bottom is supporting 500 pounds of water.... adding gravel and rocks displaces some of that, but the weight still climbs some more. Still, most of that water weight is evenly distributed.

What you want to avoid are any pressure points on the lower pane of glass...... no corners of heavy rocks pressuring one small spot. In some tanks, placing the rocks on top of the gravel works to spread out the weight, but we can't do that in our cichlid tanks (the fish will undermine the structures with their digging).

So, you can put egg crate (as suggested above) or stryrofoam along the entire bottom of the tank to spread the weight.... I've even heard of using a 1/4" or 1/2" thick piece of acrylic.

Also, as you stress the bottom pane of glass, the levelness of the tank becomes increasingly important. I use thick styrofoam sheeting under all my tanks, and it is (as suggested above) a good idea to use a sheet of plywood on top of metal stands as they can flex a little.

As the tanks get bigger, the "floating panel" design of most stock tanks goes away. You know how the bottom of most tanks don't sit on the floor but rather are supported by the edge of the frame? In a very big tank, it is necessary to make that lower pane rest flush on the floor. That further increases the stability and strength of the construction.

04-18-2003, 08:12 AM
Another thought along the lines of sharp corners would be to buy clear standard house siliconand apply a 1/4" bead on the bottom rocks perhaps in three lines and then let it dry for a day, and then gas off for an additional day. This way you could put the rock with the bead on the bottom of the tank. You would still have water flow and avoid dirrect rock to glass contact.

Furthermore if you blostered the underside with a plywood strip down the middle you'd be doing the equivalent of supporting it's fifth weak area. That should do the trick.

In my experience, had to use 1/4" tempered glass on a project before, several full sized people can stand on it if it was properly supported. The project was a coffee table with a sheet of glass about 18"x48" and three 200lbs+ peeps stood on it, it was enforced at the edges and two pieces across the middle.

Another note on it's strength. I tried once to cut this stuff, scored the heck out of it and then used hammer to tap the edge and nothing. So I swung harder still nothing. It finally self destructed when I swung hard, glass everywhere, and that was on a damaged/scored area.

So a few hundred pounds of rock and some forsight and you're more than good to go. If you have any questions about ideas feel free to email me, my fish knowledge is negligible, how ever physics and it's practicle applications are a forte of mine lol.

04-19-2003, 04:30 PM

I sure do remember your plywood dillemma.

Put up some pics when done, I'm suer it will look great, and the fish will love it!



04-20-2003, 11:51 AM
I will definately do that. Still have to put up the pics of the recently set up 120g.

And you are right, fish do love the flagstone. They swim in and out like a maze. :)

04-20-2003, 02:48 PM
What is flagstone, it sounds interesting. Is it readily available.

04-20-2003, 07:27 PM
To me, it seems like a less sharp kind of slate, and rougher texture, too. What it really is made of, I don't know. The slate I saw was way too sharp and too large to put in the tank.

It was 10 cents a pound at a local stoneyard near me. Way cheaper than the lace rock I get at the lfs ($2.99/lb).
I think it looks cool.

I will post a pic in this thread in a couple of days, after I get the tank fully landscaped. You'll be able to see it better that way.

04-24-2003, 11:09 PM
This rock is awesome! It grows algae nicely and the fish seem to love it! I think it looks cool. Very natural. Will be taking pics very soon.