1. Home

Your suggestion is on its way!

An email with a link to:


was emailed to:

Thanks for sharing About.com with others!

Most Emailed Articles

Modular and Manufactured Homes

Readers Respond: Using Outdoor Rocks

Responses: 14


Did you ever see a rock by the side of the road that you wanted to put in your aquarium? Perhaps you even stopped and took a look, then decided you didn't want to risk it. Some outdoor rocks and gravel are safe for aquarium use, while others are not. Have you used rocks from the great outdoors? Share your story with the us.

Tank rocks

Hi all I was just wondering if I could use a few of the rocks and stones I have saved from the garden. I have read all the responses on here and will try vinegar test but would it also be a good idea to boil the said items as well to kill off anything that I don’t want in the tank
—Guest alan

Outside rocks and Clay Pots

Thanks for the info on the rocks, now what about the red clay pots you can buy anywere would they be ok to put in a fresh water tank? Should I test with the Vinegar? Thanks
—Guest ILikeFishies!!

PH hardness (rocks) for Cichlids

To Greg In Toronto. I am surprised by your Cichlid post as most come from lakes where kh gh is high and as well ph. Limestone creates such an environment the opposite of low ph low hardness. (amazon for example) Limestone is know to raise not lower or make "soft" the water. Lake Malawi was formed along with the other Rift Lakes, approximately three million years ago. Rather ironically, I suppose, this happens to be the time when the first man-like creatures were also beginning to emerge in this area of East Africa. Lake Malawi is also a very large lake - it is, in fact, the ninth largest in the world, being 580 kilometres long, with a surface area of around 30,000 square kilometres, and depths in excess of 700 metres. Now we have some background knowledge about why these cichlids are so special, and before we go on to setting up an aquarium for them, what should we as serious aquarists need to know about Lake Malawi?

Salted rocks

Can I use rocks from the sea in a freshwater aquarium ? Can I soak them in the bucket that I clean the house with? How long do I soak them for?
—Guest kirk shaw

Outdoor Rocks

Yes! it is safe but you have to wash with brush and put it in the water filled bucket for 10 min. Remember that do not use any chemical for cleaning the stone.
—Guest Sohail

Unknown make-up of rocks

Outside rocks ok as long as you test with vinegar and no bubbling occurs. Rocks bearing calcium no good.
—Guest blueyeagle

Florida beach rocks

I do clean beautiful rocks I find in south florida with vinegar and rinse, let them bake in sun for a bit. I use them only in freshwater tank, not reef. They look awesome!

My Cichlid tank

I set up a 100gal (US Gal), 350 L, for my Lake Malawi Cichlids. For the tank scape I used very big `Moss rock` from the Niagara Escarpment. The rock is ideal as it is limestone based which gives the Cichlids the soft water they like, also the rock provide places to hide (but my Cichlids do not hide)....I can actuality put my hand into the tank a pat the larger fish (4 to 7 inches), they will even let me hold onto them and take them out of the tank (for only very small time of course). And breed...arrrrrrr! So no issues with these rock which I collected from the Niagara Escarpment. I just put them in the bath tub, hot water with a bit of breach. After about 6 hours I changed the water with hot water and did this for about 2 days (new water every 6 hours), then into the tank. Have never had a problem with this process. Now wood is a totally different issue. g
—Guest Greg in Toronto

Rocks at the home depot

Slate rock tiles in the flooring dept. (inert) look great in my tank. On a towel, hammer down the cut edges for a natural look, split them into 2 or 3 pieces for creating ledges or hiddy holes. Soak in vinegar and hyper wash.
—Guest hopernch

outdoor rocks safe

I have used outdoor rocks for about 15 years and have NEVER had a problem. Didn't use vinegar, boil them or even clean them. But my luck ran out a few months back when I put a boat prop in the tank. It looked great but after about 4 days, half the fish were dead and I had an oil slick!!! The prop has been cleaned and bead blasted, put back in. I wet vac'd the oil off the surface and the tank is back to being beautiful.
—Guest Greg

outdoor rocks

I have used rocks from our driveway on the farm, washed them real good with chlorine, and never had a problem! So I think it is allright.
—Guest Leny

"safe" found rocks

I've used several 'found' rocks or stones that were not necessarily manufactured for aquarium use. As long as the rocks involved have no limestone or other calciferous (SP) rock in the make-up they're fine to use. Put a few drops of vinegar on the rock in question and if the vinegar bubbles don't put the stone in question in your aquarium as it's a calcium-bearing rock. But other more glass-like rocks are fine, and quartz crystals are perfectly acceptable as well.
—Guest Oddsoxdi

Rock from along the highway

Some time ago I used to make rock backgrounds for aqs. I collected the slate like rock from road cuts where ever I traveled, including bringing a suitcase full from Alaska. Never had any negative effects, just beautiful tanks.
—Guest Greg Hall

using outside rocks

I'd be very hesitant of using your average stone from the side of the road /ditch. I myself ended up with a massive algae problem. Although I did test for metals using vinegar, algae I didn't consider. Good luck if you like that cool rock and have to have it. lol
—Guest WarEagle

©2015 About.com. All rights reserved.