Severe diatom infestation

I haven't posted on the forum in a long time, so I'm hoping that some more experienced aquarists can give me some advice on this problem that I've been dealing with the past few months, as I've ran out of ideas to remedy this.

As it says in the title, I've been dealing with a severe diatom infestation the past few months that I haven't been able to get under control. I'm not certain if it's because my city has switched the water supply or not, but I've tried different methods to reduce them, including much lighter feedings of the fish (I can't possibly reduce it any further), I've been doing heavy gravel vacs, I've tried changing the lighting intensity and adjusting the lighting schedule, more aeration & less aeration. I do bi-weekly water changes of 50-75% (I would switch to weekly, but due to my work schedule and also being a caretaker of a pair of guinea pigs too, I simply don't have the time to do it more often). I added several nerite snails a couple of months ago and although they have helped a bit, they mostly eat the diatoms on the driftwood and ignore the plants. I think that I've tried every natural method possible to no avail. I've even went as far as adding Seachem Phosguard to reduce the silicates and phospates in the water, but it didn't even make a dent.

I'm considering some more extreme methods like a complete tank back out or removing all of the current plants and replacing them with healthier ones because the coating of diatoms in the tank is so bad that it's caused the water wisteria and java fern to become anemic. I was hoping that if I increased the lighting and duration that other types of algae and the plants would take over (preferably green hair algae, which I had at one time), but instead some black beard algae has appeared too... but because the diatoms are so dominant, they actually coat the black beard algae also.

Are there other types of plants that can combat diatoms by consuming the silicates and phosphates? I've also thought about purchasing many more marimo moss balls.
I'm out of answers.... even though they're easy to remove, I'm really tired of having them. If it was light and sporadic, I wouldn't mind, but this magnitude has become unbearable anymore.

This is what is looks like after two weeks before I clean the tank:

 

Doesn’t look like diatoms to me. Looks like Cyanobacteria. Diatoms are a toast brown colour, and will rub off like powder in the water. Cyanobacteria on the other hand, stick together in a nice sheet of slime. So try out one of the remedies for that, and you won’t have to throw out your plants.

 

Doesn’t look like diatoms to me. Looks like Cyanobacteria. Diatoms are a toast brown colour, and will rub off like powder in the water. Cyanobacteria on the other hand, stick together in a nice sheet of slime. So try out one of the remedies for that, and you won’t have to throw out your plants.

I thought that cyanobacteria is blue-green in color? The coating on the plants is almost dark dark brown... almost black.

 

It doesn’t look like Cyanobacteria to me, but if it smells horrible and is slimy and easy to wipe or siphon off then it could be.

 

Diatoms require significant levels of silica in the water to build their shells. Diatom blooms are common when first starting up an aquarium with silica sand as the substrate. However, they typically die out after a couple of months. If your tap water has high levels of silica, this can also support diatom blooms. Check with your water supplier to see if your water has high levels of silica.

Cyanobacteria are bacteria that contain chlorophyll. That is why they are often called blue-green algae. However, the slime film can be various colors, even black. If the aquarium has a funky odor, it is likely cyanobacteria.

 

Diatoms require significant levels of silica in the water to build their shells. Diatom blooms are common when first starting up an aquarium with silica sand as the substrate. However, they typically die out after a couple of months. If your tap water has high levels of silica, this can also support diatom blooms. Check with your water supplier to see if your water has high levels of silica.

Cyanobacteria are bacteria that contain chlorophyll. That is why they are often called blue-green algae. However, the slime film can be various colors, even black. If the aquarium has a funky odor, it is likely cyanobacteria.

Right... I'm aware of all of this. When Lakefish said that it doesn't look like diatoms, I was a bit stumped by him saying that. It starts as the brown color that would be associated with diatoms, until it gets very thick, then it looks like it is in the picture.. almost black.

It's already pretty obvious that I have high quantities of silicates in the water, since this wasn't a problem until a few months ago and this tank has been running for 3 years. I just need some advice for something I may not have thought of already.

I decided to shut off the lights for now to help slow their growth. I need to know how to get the silicates out of the water or if it's even possible?

 

Personally I don’t think silicates are your problem at all. Diatoms just aren’t that aggressive. I’m on a well, and use local sand in my tanks, and so there is always some brown algae. Never enough to smother plants or be a problem. Cyanobacteria on the other hand, was a major problem for a time. Tried increased current, aeration, more water changes, blackout... What finally worked for me was to replace the wood I had in that tank. I think it had just reached a state of decomposition that released whatever it was that the bacteria enjoyed. That’s my theory. I only replaced the wood because it was getting mushy and I’d found another nicer piece on the beach. The algae came back less and less after cleanings. Anecdotal evidence only, but something you could try.
And for the record, I’m a “her.” Lol.

 

It's already pretty obvious that I have high quantities of silicates in the water, since this wasn't a problem until a few months ago and this tank has been running for 3 years. I just need some advice for something I may not have thought of already.

I told my friend of your situation and he thinks you have done what you can to control the issue. The only thing he suggested or wanted to know is if your lighting has ever been changed out during the 3 years your tank has been running. Lighting spectrum might be weak if it hasn't. Just a suggestion after reading your post. Hope you can work it out.

 

Personally I don’t think silicates are your problem at all. Diatoms just aren’t that aggressive. I’m on a well, and use local sand in my tanks, and so there is always some brown algae. Never enough to smother plants or be a problem. Cyanobacteria on the other hand, was a major problem for a time. Tried increased current, aeration, more water changes, blackout... What finally worked for me was to replace the wood I had in that tank. I think it had just reached a state of decomposition that released whatever it was that the bacteria enjoyed. That’s my theory. I only replaced the wood because it was getting mushy and I’d found another nicer piece on the beach. The algae came back less and less after cleanings. Anecdotal evidence only, but something you could try.
And for the record, I’m a “her.” Lol.

Sorry... didn't know that you're female. Here in Florida, there are many places where the water supply is based on underground aquafers that are heavy in mineral content, like where I live.

I'll go ahead and order a test kit to see how much silica is in the water and go from there.

 

That is severe diatoms. Generally they go from a cloud in the water, to a brown dusty layer on everything to a black coating that's hard to remove long term after a year or so if you don't clean it up at the brown stage after it's settled. I'm assuming the black layer is another form of algae grown on top of the brown layer that gets put down.

With diatoms, if you have a bloom there's three options. Option 1 is to do a huge water change and hope it disrupts it and it dies off (rarely works) but can end the bloom.
Option 2 is to do nothing but just clean surfaces and stop water changing for a month or longer until it goes clear and settles as it uses up the resource its exploiting and dies ending the bloom.
Option 3 is to get a UV sterilizer on the tank and and an in tank filter put in to capture them and then kill and polish them out of the water ending the bloom.

Your picture doesn't look like diatoms to me though. Looks like basic black algae and it would be from either excess phosphates or a carbon dioxide imbalance, too little for the plants to use for photosynthesis, but more than enough for the algae to use.

If you don't have cloudy blurry water, almost like looking through alcohol mixed with water from the distortion it causes, it's not bacterial or diatom.

This was 2 weeks ago, when I thought I broke the diatom bloom finally and did a water change and cleaned up.


I was wrong, basically the water change has started it all over, giving it new nutrients to bloom out again.

This is it right now...

 

If you do have a diatom problem and the concentration of silicates in your tap water is high, there is a possible solution. The same chemical resins that are sold to remove phosphates from the water will also remove silicates. This include products such as PhosGuard, Phos-Zorb, PhosBan, ROWAphos, Clearmax, and other products containing silica or granular ferrous oxide. The GFO products are more expensive, but tend to be more effective.,

 

Hey,

The coating on the plants is almost dark dark brown... almost black.

I would take the wood out and smell it, also check the substrate under the wood. I was helping someone with a fish tank just recently with the exact same symptoms and it was the wood rotting/decaying.

Be aware though, as it is now your tank probably doesn't smell at all. However when he cleaned out his fish tank (he restarted it), he had to throw up from the smell. Just so you're prepared in case it's the same thing happening.

 

Hey,



I would take the wood out and smell it, also check the substrate under the wood. I was helping someone with a fish tank just recently with the exact same symptoms and it was the wood rotting/decaying.

Be aware though, as it is now your tank probably doesn't smell at all. However when he cleaned out his fish tank (he restarted it), he had to throw up from the smell. Just so you're prepared in case it's the same thing happening.

My bristlenose won't like that, but I can try that.

If you do have a diatom problem and the concentration of silicates in your tap water is high, there is a possible solution. The same chemical resins that are sold to remove phosphates from the water will also remove silicates. This include products such as PhosGuard, Phos-Zorb, PhosBan, ROWAphos, Clearmax, and other products containing silica or granular ferrous oxide. The GFO products are more expensive, but tend to be more effective.,

I tried using Phosguard to no avail.

 

I have 3 tanks and one has chronic diatoms. The other 2 have none. Same source water. The only difference is the tank with diatoms is run at pH8 for the Africans. The other 2 are are at 7.5, which is also the tap pH. Also, the diatom tank has much lower lighting than the other two tanks.

I'm not suggesting it's a pH issue, but rather that the source water may not be the only possible culprit with diatoms.

You photo does not look like diatoms to me, but it's hard to tell for sure. Diatoms will easily rub off the surface. If it's adhered to surface and won't easily come off, it's not diatoms. For Diatoms, I simply add nerite snails. 5 nerites completely cleaned my 55 gal in less than a week. Every surface except the glass was covered with diatoms (a lot of rocks). The tank was brown when I added the snails. Whithin a week I was enjoying all the rock-work again.

Another possible factor is lighting. My 55 is 25 years old and so are the original florescent light fixtures. About a year ago one of the fixtures died. I replaced it with a cheap LED light. Now, the diatoms grow under the florescent light, but not under the LED side of the tank. To my eye, the lights look the same. You wouldn't see a difference in brightness or light color between the two lights. But of course plants don't care about that.

 

My bristlenose won't like that, but I can try that.

I tried using Phosguard to no avail.

If Phosguard did not help, it was probably not a diatom/silicate issue.

Phosguard is a silica based media. The GFO products are more effective, but if Phosguard did not help, the GFO products might not either.

 

I have 3 tanks and one has chronic diatoms. The other 2 have none. Same source water. The only difference is the tank with diatoms is run at pH8 for the Africans. The other 2 are are at 7.5, which is also the tap pH. Also, the diatom tank has much lower lighting than the other two tanks.

I'm not suggesting it's a pH issue, but rather that the source water may not be the only possible culprit with diatoms.

You photo does not look like diatoms to me, but it's hard to tell for sure. Diatoms will easily rub off the surface. If it's adhered to surface and won't easily come off, it's not diatoms. For Diatoms, I simply add nerite snails. 5 nerites completely cleaned my 55 gal in less than a week. Every surface except the glass was covered with diatoms (a lot of rocks). The tank was brown when I added the snails. Whithin a week I was enjoying all the rock-work again.

Another possible factor is lighting. My 55 is 25 years old and so are the original florescent light fixtures. About a year ago one of the fixtures died. I replaced it with a cheap LED light. Now, the diatoms grow under the florescent light, but not under the LED side of the tank. To my eye, the lights look the same. You wouldn't see a difference in brightness or light color between the two lights. But of course plants don't care about that.

yeah, my nuisance diatoms are also on a fluorescent lit aquarium, that may very well have something to do with it. Although I've never made the observation and connected the dots, your observation seems really relevant to me, that lighting can be contributing at least in my situation, a reason to upgrade to LED on my next light bulb replacement I suppose!

And yes, my diatoms like when they are on the glass, if you stick you hand in there and just wipe it along the glass you can see them swirl away off the glass in a cloud. they don't "stick" until much later, but I'm not sure if it's diatoms that are sticking, or it's other algae growing on the diatom layer that gets laid down, like I mentioned, just leaving them completely for a long while it becomes a black film coating thats hard to get off. I've left diatom coating for years on the back glass and let it do it's thing to see what happens. My tank with diatoms is pH6.4 currently, and it's been even lower below pH6, pH really isn't a factor if you get them up at pH8 and I get them down at pH6.

 

I have 3 tanks and one has chronic diatoms. The other 2 have none. Same source water. The only difference is the tank with diatoms is run at pH8 for the Africans. The other 2 are are at 7.5, which is also the tap pH. Also, the diatom tank has much lower lighting than the other two tanks.

I'm not suggesting it's a pH issue, but rather that the source water may not be the only possible culprit with diatoms.

You photo does not look like diatoms to me, but it's hard to tell for sure. Diatoms will easily rub off the surface. If it's adhered to surface and won't easily come off, it's not diatoms. For Diatoms, I simply add nerite snails. 5 nerites completely cleaned my 55 gal in less than a week. Every surface except the glass was covered with diatoms (a lot of rocks). The tank was brown when I added the snails. Whithin a week I was enjoying all the rock-work again.

Another possible factor is lighting. My 55 is 25 years old and so are the original florescent light fixtures. About a year ago one of the fixtures died. I replaced it with a cheap LED light. Now, the diatoms grow under the florescent light, but not under the LED side of the tank. To my eye, the lights look the same. You wouldn't see a difference in brightness or light color between the two lights. But of course plants don't care about that.

The texture is somewhat slimy and I can rub them off the plants easily. I have a huge piece of driftwood as a centerpiece in the tank, so I'll be pulling it out this weekend and see what happens. I just got the silicate test kit yesterday, so I'll go ahead and test the water too.

 

If Phosguard did not help, it was probably not a diatom/silicate issue.

Phosguard is a silica based media. The GFO products are more effective, but if Phosguard did not help, the GFO products might not either.

I've kept the lights off on the tank the past several days and there really hasn't been any growth so far.

 

I've kept the lights off on the tank the past several days and there really hasn't been any growth so far.

That only tells you that the problem involves a species containing chlorophyll. It does not tell you whether it is diatoms, black beard algae/red algae, or cyanobacteria, etc.

 

That only tells you that the problem involves a species containing chlorophyll. It does not tell you whether it is diatoms, black beard algae/red algae, or cyanobacteria, etc.

I tested the water over the weekend and the silicate level is about 4 mg/L.... I readjusted the lights on Sunday to a lower level than I was running before. I'm crossing my fingers. I haven't pulled the driftwood out of the tank yet, but if I'm noticing more growth again, I'll pull it out this weekend.

 

A silica concentration of 4 ppm is not terribly high. Hopefully, your mitigation methods will work.

 

A silica concentration of 4 ppm is not terribly high. Hopefully, your mitigation methods will work.

Hopefully.... this has been a pain in the butt for a long time.