Anyone use slate to create hiding spaces?

[bumblebee]

Well, when I began my 20 gallon tank, I decided it would be cool to use stacked slate as decoration in the back. I had lots of red, green grey and white slate that was left over from roofing my parents colonial house. Since my girlfriend used to run a landscaping crew, she built the wall for me (with a wrap around corner too) and it was extremely sturdy, with lots of little caves. I aged the tank, and it cycled magnificently. But recently, after about 4 months, I could not get my nitrates down below 30 ppm (and the loss of my flower shrimp b/c they don't like nitrates). After repeated water changes I decided that I would have to take out some of the rock and found that all the crevices were filled with waste So as of tonight I took out all the slate and did a 25% water change to get rid of all the waste. I was under the impression that others have created caves with rock with no adverse affects, but my setup did not work. Anyone with any experience here? I loved the way the rock looked, but I love my Thai Wood Shrimp too, and they can't handle the nitrate problems. Any help would be appreciated.

 

[Kryten]

The problem may not just be the waste. If you want to have a finished slate effect, you can use waterproof filler to fill small cracks that may accumulate waste, but I suspect part of your problem may be the slate itself

Most stones will give off chemicals into the water, as will wood and anything else porous. It is possible that the slate is seeping nitrates into the water. I am not too up on rock chemistry though so if anyone else can chip in, that'd be cool

 

[Dubby]

I have created rock faces using slate with no adverse reaction. As Kryten says the nitrate problem may not be entirely due to the waste.

Do you have live plants and if so how are they growing? Plants absorb nitrates quite well. So you might want to increase the live plants to see if it helps.

 

[Harmonic]

It's your lucky day. You could call me a stone expert! My business is stone masonry. I'm third generation, and have been running around at the job sites messing with rocks a long as I can remember. I went full time as a mason in 1994. So... I'm your rock man.

On rocks and leaching/seeping: I'll try my best here not to offend Kryten, but he's kinda hit and miss through out his reply. He did say he's not up on rock chemistry, so that lets him off. No big deal. Ok. When rocks leach, it's minerals and metals that are released. There can be chemical issues, but those would be from surface contamination instead of seepage.

99% of all rock that leach are sedimentry. This type of stone forms from layers of sediment at the bottom of the ocean. The reason this rock leaches is because the minerals and other elements suspended in sea water get trapped in the sediment on the ocean floor. The imense weight of the ocean compacts the sediment into solid stone. We're talking millions years ago here. As the tectonic plates move, oceans dry up and expose the sedimentary rock. This type of rock leaches so easily is because it is still the exact same thing it was millions of years ago. There was no actual phisiological change, only compression. Limestone is sedimentary, and so is sandstone. Sandstone does not leach however, as it forms under different geological conditions than limestone.

You also have igneous rock, which is produced by volcanic activity. This rock started out as something else, but the extreme heat has melted it. This heating and cooling does produce a physical change in the rock. Lava rock and granite are igneous. I have never known ingeous rock to leach or seep anything.

Then you have metamorphic rock. This type of rock forms exactly like sedimentary rock, but only where massive amounts of organics were trapped. These organics act as a catalyst for physical changes in this rock as well. Again, I have never known metamorphic to leach or seep anything. Coal and slate are exaples here. Slate is actualy one of the most leach-proof rocks there are. Think about it, they use it for roofing...


Now on your nitrate...

Yes, a lot of people use rock to create caves and other natural looking aquascapes. The difference between you and them bumblebee is surfave area. Nitrifying bacteria grow on every surface inside the tank. Someone else might have even more rock than you have weight wise, but less than half of the total surface area your little rock wall has. Basicly, you discovered the problem yourself.

Solutions...

What type of filtration do you have? Your filter media could be a nitrate factory. The tank's about 4 months old? Have you cleaned the filter out? If not that would help too.(remember never clean all your filter media at once, and when you do clean it, scrub it clean in the water cange water you take out of the tank.) I think you could put the rock wall back up after the tank re-stabilizes. I wouldn't use silicone filler, not at first. Go without for a while and try this...just simply using the siphon hose along the cracks in the wall to suck the waste out of the cracks. It should work quite well, unless your slate is cut and stacked with near zero tolerance. If the crack siphoning doesn't work, silicone filler is an option. I'm afraid though that if the silicone filling is not done thoroughly enough, it could actually add to the problem.

How often have you been water changing? I see you did a few after noticing the problem, but what about your normal water change schedule? You might consider altering your schedule by changing water more frequent in hopes of preventing another build up.

Some plants do consume nitrate, (some algaes do too) but they also consume a bunch of other stuff too. Plants can be hard to take care of, but if you had a CO2 system and power compact lighting you'd have 'em growing like weeds.

Nitrate reduction is a tricky matter. Ya just gotta find what works best for you.

 

[Fishsmurf]

Harmonics - Good post, thanks for the info......

 

[Dragonslair]

Harmonic, I did geology at uni. not hot on it but got through. I must say that I was impressed by your explaination. No jargon just plain ordinary english. Stone mason to boot!!! Well done. AND who says a woman can't make it in a mans world???

 

[Pufferpack]

Hi Bumblebee.

We also use a lot of slate in our tanks, and have run up against the same problem of waste trapped in the caves. . What we do to solve this problem is when doing a water change/cleaning we siphon out half the water we're planning to change, then using the gravel vac in reverse we pump the fresh water into the tank and use the outflow to "wash" the waste out of the caves and crevases (to do this we make sure the fresh water bucket is higher than the tank in order for the gravity feed to work). Once we have washed the caves out we continue with the cleaning as normal. Seems to work well as we no longer get excessive waste building up in the caves.

HTH

Don.

 

[bumblebee]

Wow harmonic great post! I loved the information, and I'm glad to see some people still follow the family trades. In fact like you said about slate being used for roofs, that is where i got it from. There are so many different colors it looks awesome in the tank! Pufferpack, that is a great idea! When you create the wall do you try to make the slate fit as close as possible, or leave space between so the water syphoning back in can clean it? I want to try the slate again once it is stablized. I did another 20% water change and my nitrates are down to 10, so it is lowering. Before the problem started, I was doing water changes every week, and then when I noticed that the nitrates were not going down I did them twice a week. Thanks for the information guys, I won't give up on my slate wall yet!

 

[Pufferpack]

Actually when we first built the wall I didn't think too much about it, just piled it all together. As luck would have it worked out great for the fish, as I left lots of smaller gaps and cracks, I now find that some of the fish seem to feel more secure wriggling into the tight cracks, while others like the more open caves. I guess it all depends on what types of fish are taking up residence in the wall.

 

[dolphin]

Hi bumblebee

Nitrates are the end product of the filtration process. These are the least toxic of the nitrogen compounds that are found in our tanks, and can be removed in three ways

1 Water changes.
2. Plant growth, algae and higher forms.
3. Anaerobic filtration, (filtration without the presence of oxygen).

The problem with a build up of solid waste in a tank is not nitrates, but DOC (dissolved organic compounds). Again regular cleaning and water changes will remove them from the water. Try to remove as much solids waste from your system as possible, as it will eventually cause the death of the nitrifying bacteria in the filter, and then the build up of ammonia in your tank and the death of your fish.

Dolphin