Black stuff on sand

[shells]

I recently replied in someone else's thread re: the same problem as below with no success. I'm hoping for some guidance.

I started to develop small patches of brownish algae on the glass which was easily cleaned and and am still getting this brown algae on my ornaments and fake plants and in the corners and along the bottom of my tank where the sand meets the glass. What I am most concerned about is what I can only describe as black muck appearing on my sand (its not appearing in the sand just on topand am worried is is the algae Ed mentioned:

"If the sand is deep enough then you will get anaerobic decomonsition of waste materials which can release hydrogen sulphide, which is toxic to aquatic animals. If you stir your sand and some of the sand is black or dark brown that is a sign you are getting anaerobic decomposition" (sorry I dont know how to block quoted text)

My sand is no more than 1/2 cm deep, my tank parameters are fine and the tank is about 10 months old. Its a 3ft tank holding approx 200 litres of water and I only have one Axie in it, his poop is cleaned up pretty much straight away and any unwanted food (this hardly ever happens!!) removed also. I have one java moss ball growing quite happily and the tank gets morning sun then filtered daylight the rest of the day. I also do 20% water change weekly even though there is only one axie in such a big tank (lucky little critter!)

For those who understand algae can you please give your opinion on what this black stuff appearing could be an how I can safely get rid of it?

Thanks for reading

 

[MereB]

The anerobic Bacteria Ed mentioned will first appear UNDER the sand at a depth of roughly an inch where you can see a definite reduction in the amount to light that's penetrating the sand (When the light is on).
What you are describing is nothing to be overly concerned about. It's a surface algae. I used to get it in my big tank quite a bit and it tends to make the sand on the surface stick together and clump which is easily squished and broken apart with my fingers. It and the brown algae both prefer higher pH's in my tank (7.2-7.6). I drop the pH a little (6.8-7) and it all goes away. Add a little buffer to keep it stable @ 7 and it doesn't come back again unless the pH rises again. It will rise again because you're changing water and effectively removing the minerals that buffer with your water changes

Not sure if the sand would continue to clump once ingested but I imagine the axies digestive system would be able to kill the algae which would declump the sand without causing any problems to the axie. So if you're not comfortable adding pH buffers etc to your water and were happy to live with the black surface algae I guess you could just leave it alone.

Here's a pic of the Anerobic Bacteria and how it looks. It turns the white sand grey at deeper levels but you will see a clear and thick black line where it starts just on the edge of the light's maximum depth which is about an inch which is why it's only really seen in sand that's deeper than that.
(Same tank, 2 pics joined together )

 

[shells]

Ah... thank you :happy: It's definitely not the anerobic bacteria, sounds exactly like what you describe. Hopefully Abraham hasn't ingested any as I feed him in a washed out glass jar (much less messy). I will give dropping the ph a go. Would I also benefit from doing less regular water changes given the size of the take and just keeping an eye on the Nitrate levels?

 

[theJATM]

I recently replied in someone else's thread re: the same problem as below with no success. I'm hoping for some guidance.

I started to develop small patches of brownish algae on the glass which was easily cleaned and and am still getting this brown algae on my ornaments and fake plants and in the corners and along the bottom of my tank where the sand meets the glass. What I am most concerned about is what I can only describe as black muck appearing on my sand (its not appearing in the sand just on topand am worried is is the algae Ed mentioned:

"If the sand is deep enough then you will get anaerobic decomonsition of waste materials which can release hydrogen sulphide, which is toxic to aquatic animals. If you stir your sand and some of the sand is black or dark brown that is a sign you are getting anaerobic decomposition" (sorry I dont know how to block quoted text)

My sand is no more than 1/2 cm deep, my tank parameters are fine and the tank is about 10 months old. Its a 3ft tank holding approx 200 litres of water and I only have one Axie in it, his poop is cleaned up pretty much straight away and any unwanted food (this hardly ever happens!!) removed also. I have one java moss ball growing quite happily and the tank gets morning sun then filtered daylight the rest of the day. I also do 20% water change weekly even though there is only one axie in such a big tank (lucky little critter!)

For those who understand algae can you please give your opinion on what this black stuff appearing could be an how I can safely get rid of it?

Thanks for reading

from my understanding, the black stuff is developing muck and is the sign of a very healthy tank, actually. i have it going on too, and its unsightly. i also have the algae problem as well. im just doing more water changes to remove excess nitrites hoping thatll help.

 

[MereB]

from my understanding, the black stuff is developing muck and is the sign of a very healthy tank, actually. i have it going on too, and its unsightly. i also have the algae problem as well. im just doing more water changes to remove excess nitrites hoping thatll help.

Algae uses nitrates rather than nitrites and I'm hoping that's what you meant as if you have excess nitrites in your tank than you have bigger problems with it than just some algae. Rapid growth or excessive amounts of algae is a sign of high nitrates and it would be best to sort that out first but no matter what you do you will never get rid of all the algae. Even if you don't see it on any surfaces there will still be some microscopic spores floating around in the water just waiting for the chance to take hold and grow like nuts. Your best bet is to control it by keeping nitrates down which can be done with water changes and the use of live plants who will compete with the algae for the nitrate. So if you have high Nitrates then yes water changes will help but you probably wont see much success if you haven't removed all the algae you can from your surfaces first and sucked that out of the tank as best you can.

You shouldn't have to change the water more than once a week as a maximum, as nitrate is quite slow to build up and excessive water changes are not only a pain in the butt they can also be a little stressful for the occupants of the tank.

If you're having to change water in a fully cycled tank more than weekly to fortnightly because of high water test readings for ammonia and nitrite then there is something going on that shouldn't be and in an axie tank it will likely be an inadequate filter for the tank and livestock you have. Often we will get a slightly too small filter in an effort to reduce the water flow but if the filter is too small it won't house sufficient bacteria to cope with the volume of waste the animals produce so you will get amounts above zero for ammonia and nitrite that necessitate a water change. Fix the problem or you will be cycling your tank forever.

There is a difference between the muck that builds up and the surface algae that sticks your sand together. 1st the gunk is more of a sludge and is fairly easily removed with a vigorous vacuum, does not stick the sand together in clumps and is typically a medium to dark brown where as the algae sticks fast to the sand causing it to clump together when disturbed and must be 'killed' to be removed. This algae is black or green-black and it also goes white once it's dead so you likely wont see it once it is.
The other notable difference between the algae and the gunk is that a drop in pH will see the algae decrease in number withing a day or two but will obviously have no affect on dirt and gunk.
You may also find that you get an aquarium 'dust' that accumulates in hard to reach and still areas of your tank and that too is decaying matter from everything in your tank but it will not stick to your sand and is a sign of poor cleaning more than anything else. It's the same dirt that you remove from your filter when you clean it out. It's not a major drama in the filter for quite a while but it will look awful in your tank.

Unfortunately I don't think I have pics of these 3 problems and I don't think I have any of them going on in any of our tanks at the moment either but I will have a look. It is almost the end of the week and a couple of hubbys shrimp tanks are coming up to due for a clean over the weekend now that the females aren't berried so you never know

My tanks are extremely healthy and always have been. I've been doing this for quite a while now and hubby has been at it even longer.

Shell - I clean my tanks, once established and stable and barring disaster, when they need it. So when it starts to look a little dirty or when nitrates get out of proportion which, with as many live plants as I have, is not often. The build up of dirt is the usual reason for me messing around in my tanks and the water change happens as a result of vacuuming the sand. If I didn't have the live plants though it could be the other way around with nitrates being more of an issue especially if you remove axie poop as you see it.
Every tank is different and I trade off the extra dirt the plants make for lower nitrates and more stable water. That of course is personal preference. Some people love flake plants and will happily take the nitrates and more frequent water changes over the mess and care of live ones but that's just no me

Mere.

 

[carsona246]

I wish I could find the article I read on freshwater deep sand beds, but one lady created a dsb in her freshwater tank, and had 5-8 inches of sand in her tank. She actually buried a guppy that had died underneath the dsb so that you could see it through the glass, and kept a record of her nitrate readings, but she also had plants so who knows if the thing actually reduced nitrates

But the interesting thing was even with the dead fish buried underneath the sand(and obviously large amounts of anaerobic bacteria), her fish were perfectly healthy. I think the danger of anaerobic bacteria growing in sand is a little over-exaggerated. this lady had this tank up and running for 1+ years and nothing had gone wrong.

Now I'm not going to go out running and try out one of these freshwater dsb's, because one of the critical components in a dsb filtration design is the micro organisms saltwater has. However, I do know people who have been attempting to use dsb filtration for more than 2 years, and have had no accidents in their tank, with pretty active fish that would stir the surface sand up. I don't think you have to worry about anaerobic bacteria growing under the sand

 

[MereB]

@ Carsona - LOL that's great! If you ever find it let me know? Sounds like an interesting little experiment. Don't suppose she took pictures of the guppy as it rotted :wacko:

I think the danger of anaerobic bacteria growing in sand is a little over-exaggerated.

I don't think you have to worry about anaerobic bacteria growing under the sand

I couldn't agree more! People worry too much about it. Hubby uses dsb's on most of his tanks because that's what he likes and because it's better for planting his plants into and he's never had a problem with gas bubbles or his water either

 

[carsona246]

She did actually take pictures of it as it rotted, it was pretty rancid looking after a couple weeks. There was a massive black spot in the sand, it looked extremely menacing.
Someone posted the article on a forum, and I can't seem to find it, I'll keep looking, it was an interesting read.

 

[shells]

Thanks heaps guys :happy: I can stop stressing now and just try subtle changes to the ph to try and rectify my problem.

That article definitely sounds interesting.....