Black algae covering sand in my shell dweller tank

[Gannon]

Hello. Below is a picture of my shell dweller aquarium which is just constantly overrun with this black algae that mostly covers the top layer of the sand. It kind of binds together with the sand making a pretty firm layer that I routinely go to break apart for it to always come back. This algae isn't in any of my other tanks so there is certainly a root problem that needs addressed. 

I assume this is excess nutrients or something like that. I wanted to do this tank entirely without plants, but I'm probably going to have to try to plant the tank to tackle these excess nutrients. I've been doing a lot of water changes to not much effect and reducing my lighting period somewhat recently. Any other advice for me in tackling this problem? I miss the pearly white sand this tank used to have with the fish able to move it around more freely. 

Update: Nitrate is only 5ppm, making it slightly harder for me to believe this is an issue with nitrates. Maybe some other nutrient is behind it. 

Edited September 14, 2022 by Gannon
update

[Gannon]

Also got on rocks but a little hot water under the sink will kill it off the rock within the next few days. 

[crcarver89]

Hi @Gannon. What kind of sand are you using? And how long as the tank been set up? My old freshwater setup used pool filter sand and it did this for about 4 months, but it cleared on its own. 

[Gannon]

On 9/14/2022 at 3:51 PM, crcarver89 said:

Hi @Gannon. What kind of sand are you using? And how long as the tank been set up? My old freshwater setup used pool filter sand and it did this for about 4 months, but it cleared on its own. 

This tank was set up for 3 months before this happened and this is some caribsea sand I got for next to nothing but it was new in packaging and everything. The tank itself is many years old now, but the current scape and stocking is about 10 months. 

Edited September 14, 2022 by Gannon

[crcarver89]

On 9/14/2022 at 4:53 PM, Gannon said:

This tank was set up for 3 months before this happened and this is some caribsea sand I got for next to nothing but it was new in packaging and everything. The tank itself is many years old now, but the current scape and stocking is about 10 months. 

So this has been going on for 7ish months? Yeah, that's a tough one. It definitely seems to be excess nutrients to me, but I'm certainly no expert. As a matter of fact, my next project was looking to be shell dwellers as well. I'll keep checking in to see if anything changes. Good luck!

[nabokovfan87]

On 9/14/2022 at 1:40 PM, Gannon said:

Also got on rocks but a little hot water under the sink will kill it off the rock within the next few days. 

What sand is this?

On 9/14/2022 at 1:53 PM, Gannon said:

This tank was set up for 3 months before this happened and this is some caribsea sand I got for next to nothing but it was new in packaging and everything. The tank itself is many years old now, but the current scape and stocking is about 10 months. 

It's interesting because I've only seen issues like this on the saltwater side. It looks bacterial to me, or something more like a saltwater setup than a freshwater one.  Caribsea sells both fresh / salt products and I can't really say which is which.

Right now, I would remove all fish, remove all hardscape, remove the plants for the time being and then drastically siphon the sand clean.  Start there.... Dip the plants in RR treatment (pinned link in the journals/photos category) and then go ahead and treat the hardscape (rocks/wood) with hydrogen peroxide or another dip.

[anitstuk]

Have you tried sucking the algae clean off the sand.. I think if there is no more algae on the sand, it might not be able to grow.

[Gannon]

On 9/14/2022 at 6:11 PM, anitstuk said:

Have you tried sucking the algae clean off the sand.. I think if there is no more algae on the sand, it might not be able to grow.

Impossible, its too heavy and also breaks apart leaving little bits everywhere, under the sand, etc.

On 9/14/2022 at 6:02 PM, nabokovfan87 said:

What sand is this?

It's interesting because I've only seen issues like this on the saltwater side. It looks bacterial to me, or something more like a saltwater setup than a freshwater one.  Caribsea sells both fresh / salt products and I can't really say which is which.

Right now, I would remove all fish, remove all hardscape, remove the plants for the time being and then drastically siphon the sand clean.  Start there.... Dip the plants in RR treatment (pinned link in the journals/photos category) and then go ahead and treat the hardscape (rocks/wood) with hydrogen peroxide or another dip.

I just dont think this would work, it gets on glass and everything too. I'd have to nuke the whole tank. Maybe thats worth it at some point, but I always have some fry and stuff I'm trying to raise, the parameters aren't the same as my quarantine tank (RODI). It just seems like a lot of effort and risk for something I genuinely don't see working. 

On 9/14/2022 at 6:02 PM, nabokovfan87 said:

What sand is this?

It's interesting because I've only seen issues like this on the saltwater side. It looks bacterial to me, or something more like a saltwater setup than a freshwater one.  Caribsea sells both fresh / salt products and I can't really say which is which.

Right now, I would remove all fish, remove all hardscape, remove the plants for the time being and then drastically siphon the sand clean.  Start there.... Dip the plants in RR treatment (pinned link in the journals/photos category) and then go ahead and treat the hardscape (rocks/wood) with hydrogen peroxide or another dip.

This is also definitely sand made for freshwater, though I doubt that matters. 

[Gannon]

On 9/14/2022 at 4:05 PM, crcarver89 said:

So this has been going on for 7ish months? Yeah, that's a tough one. It definitely seems to be excess nutrients to me, but I'm certainly no expert. As a matter of fact, my next project was looking to be shell dwellers as well. I'll keep checking in to see if anything changes. Good luck!

I'm hoping that I can just get rid of this and enjoy my tank. I added some plants to the tank like val and pogostemon, should be good nutrient absorbers, maybe they'll help. I'll try anything to avoid resetting the whole thing for it to inevitably come back haha. Both times I've reset tanks in the past did nothing to combat this kind of algae, bacteria, hydra, or whatever issue. 

[nabokovfan87]

On 9/14/2022 at 4:29 PM, Gannon said:

I just dont think this would work, it gets on glass and everything too. I'd have to nuke the whole tank. Maybe thats worth it at some point, but I always have some fry and stuff I'm trying to raise, the parameters aren't the same as my quarantine tank (RODI). It just seems like a lot of effort and risk for something I genuinely don't see working. 

You would or should be doing something similar once in a while. Gravel vac, move decor, etc. Especially with sand. There's something going on and completely removing what you need to (fish and hard scape) so you can sift as much out of the sand is the best advice I think I can give you.

Once you get the sand clean, you can figure out what exactly is going on and how it's spreading. That's a huge infestation and it doesn't look like algae.

Maybe others have seen something like this...? @Biotope Biologist

[Gannon]

On 9/14/2022 at 9:41 PM, nabokovfan87 said:

You would or should be doing something similar once in a while. Gravel vac, move decor, etc. Especially with sand. There's something going on and completely removing what you need to (fish and hard scape) so you can sift as much out of the sand is the best advice I think I can give you.

Once you get the sand clean, you can figure out what exactly is going on and how it's spreading. That's a huge infestation and it doesn't look like algae.

Maybe others have seen something like this...? @Biotope Biologist

I should've made in clear in the original post, I have tried gravel vaccing, it doesn't work cause binded with the sand and too heavy. I have move decorations out, I have scooped out all of it with nets before, I've done a lot of things to remove it temporarily and it means/results in nothing. its also impossible to get it all as it breaks apart and covers surfaces too, and not obviously since its so dark you can't see it on most black parts of the tank. 

In my mind it seems pretty firmly as an issue that has a root cause that needs fixed. I cross contaminate with all my tanks because I need more buckets, siphons, and space and money to get those. This has't been a problem in any of my tanks, except this one. I also found old photos that show this stuff was on my dragonstones in old setups for this tank 3+ years ago. It is only this fluval flex tank for some reason I don't understand. 

Edited September 15, 2022 by Gannon
more detail

[Biotope Biologist]

Yup I’ve seen this before. In my experience it only happens with finer sands thus I tend to avoid them all together. 
 

The only solution I have that will work long term is burying heater coil under the sand. It will create a convection current which will keep your sand bed moving and the algae won’t have the photoperiod they need to establish. 

 

[Gannon]

On 9/15/2022 at 10:20 AM, Biotope Biologist said:

Yup I’ve seen this before. In my experience it only happens with finer sands thus I tend to avoid them all together. 
 

The only solution I have that will work long term is burying heater coil under the sand. It will create a convection current which will keep your sand bed moving and the algae won’t have the photoperiod they need to establish. 

 

I've never heard of this before. Can you link me what you're talking about? Would this be a problem if my shell dwellers dig up sand and uncover the coil? Is there any chance this stuff goes away? 

[Biotope Biologist]

You’ll want something like this:

https://www.heatingelementsplus.com/5-w-ft-240v-self-reg-heating-cable-tpe-overjacket.html?gclid=Cj0KCQjwmouZBhDSARIsALYcouqprkFS1egHSVJrfPQW0DxRxbtEE3LOjIXwfmq7V7zwtV_QmPvoc0oaAmGVEALw_wcB
 

be sure to max out at 5-10w it’s just enough heat to establish convection, not to boil your fish. These heat cables are often used in pool piping in the north to keep the water from freezing. They used to make this stuff for aquariums I thought but perhaps I dreamt it…

 

itll go away it just takes time. It is unsightly though. Turns your sand into spoiled milk look 🤢

Edited September 15, 2022 by Biotope Biologist

[Gannon]

On 9/15/2022 at 10:56 AM, Biotope Biologist said:

You’ll want something like this:

https://www.heatingelementsplus.com/5-w-ft-240v-self-reg-heating-cable-tpe-overjacket.html?gclid=Cj0KCQjwmouZBhDSARIsALYcouqprkFS1egHSVJrfPQW0DxRxbtEE3LOjIXwfmq7V7zwtV_QmPvoc0oaAmGVEALw_wcB
 

be sure to max out at 5-10w it’s just enough heat to establish convection, not to boil your fish. These heat cables are often used in pool piping in the north to keep the water from freezing. They used to make this stuff for aquariums I thought but perhaps I dreamt it…

This seems potentially a tad overcomplicated so I guess I'll just change to a laarger grain sand if I can't get this down with plants and shorter photoperiod. 

[Biotope Biologist]

On 9/15/2022 at 8:58 AM, Gannon said:

This seems potentially a tad overcomplicated so I guess I'll just change to a laarger grain sand if I can't get this down with plants and shorter photoperiod. 

Good luck! 
 

Plants can definitely help!

[eatyourpeas]

I get this algae in my SW tank every now and then.

I control it by cutting down the light period. The tank gets direct sunlight some months, and this definitely contributes to its presence. I do not vacuum or do anything in the tank. Also, a chiton now lives there and does laps consuming the algae that grows under the surface.

I sometimes want to encourage it as a food source for some of the critters.

Edited September 15, 2022 by eatyourpeas

[nabokovfan87]

On 9/14/2022 at 7:44 PM, Gannon said:

I should've made in clear in the original post, I have tried gravel vaccing, it doesn't work cause binded with the sand and too heavy. I have move decorations out, I have scooped out all of it with nets before, I've done a lot of things to remove it temporarily and it means/results in nothing. its also impossible to get it all as it breaks apart and covers surfaces too, and not obviously since its so dark you can't see it on most black parts of the tank. 

In my mind it seems pretty firmly as an issue that has a root cause that needs fixed. I cross contaminate with all my tanks because I need more buckets, siphons, and space and money to get those. This has't been a problem in any of my tanks, except this one. I also found old photos that show this stuff was on my dragonstones in old setups for this tank 3+ years ago. It is only this fluval flex tank for some reason I don't understand. 

I've run 3 different types of the caribsea sand. I've never had issues like you're experiencing, and I do have a tank infested with BBA/staghorn.  I have photos and such in the link in my description.  When you're saying it's coating the sand, I understand what you're saying. The sand sort of clumps together or little bits of organic material sort of spider web and suck in everything.  In terms of tank setup I do have a few questions if we are confirming this is indeed an algae.

A.  How is water flow in the tank? What is your maintenance schedule specifically in terms of how often you manually turn over sand for gas pockets?  How thick is your sand layer?
B.  Coming from the old rocks makes a ton of sense. Again, I would take those out, treat them / sterilize them with bleach and then go ahead and use dechlorinator (and then let them air dry) to remove any organic issues.
C.  Are you seeing this in your filter? Is the filter working effectively given any clogging issues with this stuff inside the impellers?
D.  Are you running an airstone in addition to your other filters?

When you get that type of a sand issue, you're going to end up scooping out, siphoning out, etc. that top layer of sand.  You have to remove it and losing some sand in that process is unfortunately going to happen.  If we know everything is working correctly and every aspect of the tank is running fine.... water parameters, equipment, fish health, dosing, lighting, co2, etc. then we should be focused manual removal and sanitizing the items that are causing this stuff to host this algae.  If you think it's dragonstone it could be due to the composition of the stone and the mud pockets inside of it.  They can be insanely deep and using something to get way inside those chambers and clean it out might be a major step.  I had one that was cleaned heavily, but after sitting in a tank for a year I took it out to deep clean it again (thanks snails) and was surprised at how much mud came out.

On 9/15/2022 at 8:56 AM, Biotope Biologist said:

be sure to max out at 5-10w it’s just enough heat to establish convection, not to boil your fish. These heat cables are often used in pool piping in the north to keep the water from freezing. They used to make this stuff for aquariums I thought but perhaps I dreamt it…

Would something like the reptile mats work that go under the tank?  Not sure they can take the load and weight of a tank, but that's the only equivalent I've seen.

Here's a video of one method on how to set it up, they definitely exist!
 

 

[Gannon]

On 9/15/2022 at 11:05 AM, nabokovfan87 said:

I've run 3 different types of the caribsea sand. I've never had issues like you're experiencing, and I do have a tank infested with BBA/staghorn.  I have photos and such in the link in my description.  When you're saying it's coating the sand, I understand what you're saying. The sand sort of clumps together or little bits of organic material sort of spider web and suck in everything.  In terms of tank setup I do have a few questions if we are confirming this is indeed an algae.

A.  How is water flow in the tank? What is your maintenance schedule specifically in terms of how often you manually turn over sand for gas pockets?  How thick is your sand layer?
B.  Coming from the old rocks makes a ton of sense. Again, I would take those out, treat them / sterilize them with bleach and then go ahead and use dechlorinator (and then let them air dry) to remove any organic issues.
C.  Are you seeing this in your filter? Is the filter working effectively given any clogging issues with this stuff inside the impellers?
D.  Are you running an airstone in addition to your other filters?

When you get that type of a sand issue, you're going to end up scooping out, siphoning out, etc. that top layer of sand.  You have to remove it and losing some sand in that process is unfortunately going to happen.  If we know everything is working correctly and every aspect of the tank is running fine.... water parameters, equipment, fish health, dosing, lighting, co2, etc. then we should be focused manual removal and sanitizing the items that are causing this stuff to host this algae.  If you think it's dragonstone it could be due to the composition of the stone and the mud pockets inside of it.  They can be insanely deep and using something to get way inside those chambers and clean it out might be a major step.  I had one that was cleaned heavily, but after sitting in a tank for a year I took it out to deep clean it again (thanks snails) and was surprised at how much mud came out.

Would something like the reptile mats work that go under the tank?  Not sure they can take the load and weight of a tank, but that's the only equivalent I've seen.

Here's a video of one method on how to set it up, they definitely exist!
 

 

I turn over the sand often because of this algae or whatever it is, there is a fairly thick layer. And when I've reset my tank and even recently I've sterilized these rocks. It just comes back from something else. Flow in the tank is pretty darn good and no I don't think I see this in my filter but then again i suppose I couldn't see a black algae on black materials. I'm not running an airstone as that wouldnt be a good mix with the fine sand. 

It's also not the dragonstone causing the issue. I've had these same exact pieces in other tanks with no issues as well as pieces that came along with these still in those other tanks. Like I said before, because of this I'm confident its some other issue with the tank, and not the rocks or sand themselves. 

Edited September 15, 2022 by Gannon

[Chick-In-Of-TheSea]

On 9/15/2022 at 12:11 PM, Gannon said:

I turn over the sand often

Yeah, I do that with a turkey baster. I suck some sand up, and then I just squeeze the baster to put it back down and it looks refreshed.

[Gannon]

On 9/15/2022 at 11:12 AM, Chick-In-Of-TheSea said:

Yeah, I do that with a turkey baster. I suck some sand up, and then I just squeeze the baster to put it back down and it looks refreshed.

I do this and also with my hands and aqquascaping tools but the chunky broken up bits of this growth still litter the top. Still looks better than before! At least for a day or two haha

On 9/15/2022 at 11:05 AM, eatyourpeas said:

I get this algae in my SW tank every now and then.

I control it by cutting down the light period. The tank gets direct sunlight some months, and this definitely contributes to its presence. I do not vacuum or do anything in the tank. Also, a chiton now lives there and does laps consuming the algae that grows under the surface.

I sometimes want to encourage it as a food source for some of the critters.

It does look so much like that saltwater stuff. Never seen this in fresh before.

[nabokovfan87]

On 9/15/2022 at 9:11 AM, Gannon said:

I'm not running an airstone as that wouldnt be a good mix with the fine sand. 

You can run an airstone without burying it in the substrate.  I use suction cups on the glass about 1" above the substrate.
 

On 9/15/2022 at 9:11 AM, Gannon said:

I turn over the sand often because of this algae or whatever it is, there is a fairly thick layer.

Anything over 4", over 6" for certain, I think you run a higher risk of issues.  Just meaning, if you need to remove some it wouldn't be a bad thing. 

On 9/15/2022 at 9:11 AM, Gannon said:

Like I said before, because of this I'm confident its some other issue with the tank, and not the rocks or sand themselves.

What are the water parameters? Phosphates and Iron can also cause BBA/Staghorn as well as nitrates being relatively high.  What equipment are you specifically running? What filter, what light?  Your OP says 5 ppm nitrates, what is it today?

[Gannon]

On 9/15/2022 at 11:24 AM, nabokovfan87 said:

You can run an airstone without burying it in the substrate.  I use suction cups on the glass about 1" above the substrate.
 

Anything over 4", over 6" for certain, I think you run a higher risk of issues.  Just meaning, if you need to remove some it wouldn't be a bad thing. 

What are the water parameters? Phosphates and Iron can also cause BBA/Staghorn as well as nitrates being relatively high.  What equipment are you specifically running? What filter, what light?  Your OP says 5 ppm nitrates, what is it today?

My sand layer is not anywhere near 4 inches so no need to worry there. And ill look into such an airstone setup. 

I don't know my phosphates as I don't have a test kit for that, but nitrates are still 5ppm or less probably. I'm running the standard fluval flex filter equipment without the carbon and biorings instead. The fluval flex tank light as well. 

[Flumpweesel]

No idea if they would be suitable with the shell dwellers but would trumpet snails help? 

 

[Gannon]

Update on this: With the addition of plants to the tank I've noticed that the grow of this stuff has slowed down a noticeable amount. Hopefully this continues to be the case.