Tank Goes Murky Overnight!

[Stubaan]

Hey folks

I have a 20 gallon long that has been running just fine for over 6 months (my first tank though). When I started it I grabbed a whole bunch of sand from a river bed at the bottom of our garden in the hopes of getting a few cool "natural" critters and maybe some sharks teeth (people find them in the streams around Gainesville, Fl, which is where I live). While the sand looks great and the cone snails seem to love burying themselves in it, it is a serious pain the gluteus maximus! I can't siphon the tank from the bottom because the sand is too fine and just gets sucked up, along with tons of helpless baby snails. And every time the bottom is disturbed, say by adding a new plant, extremely fine sediments are suspended and the tank becomes murkier - if I'm careful I can keep it to a minimum, but if the bottom is disturbed a lot there's not much I can do about it. The murkiness seems to be a colloidal suspension that never settle out, and I literally have to leave it to the filter to clear up the water again.

Saying all that, I have learned to keep this issue to a minimum by changing the water regularly (since I can't clean the sediments) and by making the changes with a bucket by submerging it, which doesn't cause any turbulence or stir things up.

I recently added a spotted pleco who is significantly bigger than the rest of the fish in the tank (4 or 5 inches as opposed to the largest other fish I have, a black widow tetra of maybe 2 inches) to help keep the algae in check. Algae seems to do well, presumably because I can't flush out the sediments and associated nitrate from settled droppings and missed food etc. And then yesterday I added two small crabs, a red clawed and a mini crab. In total, I probably have 17 or 18 inches of fish in the tank now, which I don't think is overstocking for a 20-gallon (with a 30-gallon filter).

I got home last night after having added the crabs in the afternoon, along with a piece of driftwood so they could get out of the water, and the tank was inexplicably murky. It had been clear when we left yesterday evening, but was still murky by lunch time today. One neon tetra dead and one glowfish who does not look likely to make it

So, my question: is there any reason why a tank might go murky overnight (or even more quickly in this case). At this point I am putting it down to the pleco either getting a fright or a crab nip (though these crabs are only about the size of the pleco's tail!) and violently flicking his tail when it was resting on or near the bottom, and thus starting this mess. The pleco does have a favourite spot he likes to hang out on, with his tail close to the bottom, so it at least seems like a feasible explanation. But I thought it worth checking if there could be any other possible way to account for such quick murkification.

If anyone has any advice for dealing with sand beds I'd be interested in hearing that also. I've tried siphoning from just above the bed but this seems to be a fruitless effort. Not to mention that I can make a 50% water with a fraction of the time and effort that even a small change by siphon would take (especially since I invariably have to collect and return all the tiny snails that would otherwise be discarded with the water.

And finally, is there anything I can do to help out this glowfish? It's just floating helpless near the surface, occasionally floating on its side, or with head sinking down, but also occasionally making an effort to swim... I feel really responsible for these little guys and hate to see them suffering

Thanks very much. This can be one bittersweet hobby on the heart sometimes, huh?

 

[Mr Bliss]

This is what happens with substrates that haven't been heavily rinsed. I have a similar situation with a substrate that has fine sand on top and soil underneath. In my case I've found the culprit: my bristlenose is digging a cave (make that a bristlenose mansion!) underneath my largest piece of bogwood. As plecos can't dig by moving stuff with their mouths the way cichlids do, what they do is they push their head into an opening and just wave their tail furiously, sending the substrate flying. This can cloud the water real fast if there's suitably fine sediment in the substrate (mine has fine clay in the bottom soil!).

Fine mechanical filter pads haven't done much for me as they get completely clogged in less than 24 hours. But I feel optimistic that the day will come when the bristlenose feels she has dug deep enough. In my experience substrate-based cloudiness is never a permanent problem even in tanks with heavily digging fish like convicts. Eventually they'll have "rinsed" the entire substrate.

Having said that, murkiness over a very short time period sounds more like a bacterial bloom to me, or in this case a combination of sediment and bacteria. Bacterial blooms can turn a tank from crystal clear to cloudy in an hour. It could be that the pleco has disturbed the substrate, causing it to leach out ammonia and organic molecules that promote bacterial growth in the water column. The addition of the pleco in the first place could contribute to this, as plecos produce lots of waste compared to their size. If I were you I'd keep up with the water changes and keep a close eye on my ammonia and nitrite levels.

 

[Stubaan]

Funny you should mention that about your bristlenose, because I see my pleco now has a new spot under the drift wood I just put in. Maybe the little bugger was trying to make himself a little more comfy.

Not quite sure what to do now... I guess just wait and see if it happens again, which it hopefully won't. There is a loooooooot of area for him to do this over and over and over again all over the place without the sediments ever getting "clean". Do you have any idea why most of the fish would be fine, but two are so badly affected that they die? Seems a little inconsistent, especially considering there were other fish of the same species in the tank who have shown no adverse side effects.

 

[Stubaan]

This is what happens with substrates that haven't been heavily rinsed. I have a similar situation with a substrate that has fine sand on top and soil underneath. In my case I've found the culprit: my bristlenose is digging a cave (make that a bristlenose mansion!) underneath my largest piece of bogwood. As plecos can't dig by moving stuff with their mouths the way cichlids do, what they do is they push their head into an opening and just wave their tail furiously, sending the substrate flying. This can cloud the water real fast if there's suitably fine sediment in the substrate (mine has fine clay in the bottom soil!).

Fine mechanical filter pads haven't done much for me as they get completely clogged in less than 24 hours. But I feel optimistic that the day will come when the bristlenose feels she has dug deep enough. In my experience substrate-based cloudiness is never a permanent problem even in tanks with heavily digging fish like convicts. Eventually they'll have "rinsed" the entire substrate.

Having said that, murkiness over a very short time period sounds more like a bacterial bloom to me, or in this case a combination of sediment and bacteria. Bacterial blooms can turn a tank from crystal clear to cloudy in an hour. It could be that the pleco has disturbed the substrate, causing it to leach out ammonia and organic molecules that promote bacterial growth in the water column. The addition of the pleco in the first place could contribute to this, as plecos produce lots of waste compared to their size. If I were you I'd keep up with the water changes and keep a close eye on my ammonia and nitrite levels.

I thought I should follow up with the latest on this little issue. By the end of the day the murkiness was still present and I noticed a layer pretty thick bacteria (I presume it was bacteria; it looked gray and gel-like, which I associate with bacteria) all over the driftwood. It was building up nowhere else in the tank that I could see (except perhaps suspended in the water column), so I removed the driftwood and left it in some bleach and water overnight. By morning the tank was almost clear and by the time I got home from work it was back to normal. The driftwood is now sitting outside sunbleaching.

In the past, anything that I have added I have bleached - rocks and a big shell is pretty much it. The driftwood I did NOT bleach - I guess I just assumed it wouldn't be a problem. And apparently I am an idiot, because thinking about it now it seems that a piece of driftwood being handled by a bunch of people in Petsmart as it sits on the shelf for who-knows-how-long is probably likely to have a few bacterial critters hitchhiking. I do find it strange that the bacteria was only building up on the driftwood - is that because it's a carbon source? Why would bacteria not build up on the plants, or rocks with a thick layer of algae on them?

Will the bleaching I have done to the driftwood be sufficient to prevent this happening again? I'm a little reticent to just plop it back in the tank without fully understanding its role in the outbreak. And of course I'm just assuming it was a bacterial outbreak and not fungal...

Any insights from the more experienced would be great!

Thanks!