Getting rid of diatoms in a brackish tank

Bred · Post by **Bred** » Thu Jun 16, 2005 11:20 am

Deja Vu... I've done this before!

30 watts incandescent is not intense lighting. It equates to about 5W fluorescent, in terms of intensity. The WPG rule applies to fluorescent light.

Incandescent is not a good choice for aquaria because of its narrow spectrum and heat generation. A 13W single tube fluorescent would be my choice for your tank. It will probably encourage other types of algae, which may or may not be desirable.

entropy · Post by **entropy** » Thu Jun 16, 2005 11:58 am

whoa. lots of replys. thanks guys.

Jayhawk: They're cheapo incandescent bulbs, not flourescent, so its not really 3 wpg. Light should have no effect on diatoms because they are not photosynthetic, Infact, in a freshwater tank they're growth is apparently encouraged by not enough light as they dont have algae to compete with. Since the only algae I've seen in my tank is the blue green variety, I dont want to go this route.

I'll switch out the sandstone and see if it helps. Meatball needs a new aquascape anyway:)

Has anyone actually tried phos-guard to control this stuff?

ingo_1978 · Post by **ingo_1978** » Thu Jun 16, 2005 12:08 pm

well the room my puffer is in is fairly bright, not direct sunlight though... so he does get 12 hours of light, just not 12 hours of direct light.

Could switching to a 15w flourescent bulb do the job then?

Jayhawk · Post by **Jayhawk** » Thu Jun 16, 2005 12:48 pm

It's been so long since I've had incandescent on my tanks I'd forgotten they don't go by the WPG rule! I was thinking a fluorescent would provide light for better forms of algae to possibly grow instead of diatom algae. I'd try increase flourescent lighting as diatom algae supposedly is suppressed by good light as opposed to indirect or incandescent light.

Light will not cause blue-green algae to form - that's a water parameter issue...and so are diatoms (along with low light).

Also, try to find some duckweed (it's probably a free nuisance plant at your LFS - it'll grow like mad and help decrease algae in your tank) or floating water sprite (which is surviving fine in my brackish tank, duckweed will do well, java fern is another option). Plants with good lighting will help if they survive the brackish water. I know lots of folks have had problems in BW, but in low level with the plants being slowly acclimated to slightly increasing BW mine are thriving and I think duckweed likely will thrive in darn near anything.

Edit: Removing your sandstone sure won't hurt, but I'm not convinced silicate sand or sandstone has much impact on diatoms in an established tank. I've had more issues with diatoms in argonite substrate tanks than in my tanks with silicate sand substrates (I used argonite in my tanganyikan tanks).

Eric

entropy · Post by **entropy** » Thu Jun 16, 2005 1:41 pm

Actually, Blue green algae is photosynthetic so it is affected by light. Since BGA is the only algae I've seen in my tank at this SG I really dont want to try the more light thing.

I'lll pick up some phosguard from the LFS this weekend and see if it helps.

Jayhawk · Post by **Jayhawk** » Thu Jun 16, 2005 3:14 pm

Well, yes, BGA is photosynthetic, but it's actually cynobacteria. Light won't cause an outbreak of BGA by itself unless your tank is infected with the bacteria.

Here is the best discussion on cynobacteria that I'm aware of:
http://www.thekrib.com/Plants/Algae/cyanobacteria.html

As for phosguard, I've never tried it. Plants really are the best thing I've found at combating any form of algae since with good lighting and good water parameters they tend to outcompete algae.

My water sprite (Ceratopteris thalictroides or C. pteroides - I've seen the plant pictured and labelled both ways), duckweed and java fern have now been in BW for a month, and I'm having to throw out water sprite becuase it's just growing like mad (I have a 60 watt full spectrum fluorescent bulb about a foot above the tank).

Eric

Feathers&Fins · Post by **Feathers&Fins** » Thu Jun 16, 2005 4:03 pm

chriscenter1 wrote:How does one test for silicates?

You can buy a Silicate Test Kit. For exampleâ€¦
http://www.drsfostersmith.com/Product/P ... 004+113565

I've had a very bad diatom problem since switching from Ohio River surface water to well water. Apparently well water has a much higher amount of organics/nutrients.

IMHO, skimmers do not remove any significant amount of waste material from brackish tanks unless overfeeding or a lack of water changes is involved.

I use PhosGuard in my brackish tanks. It is expensive and wastes a great deal of water by having to be pre-rinsed. My experience has been that it slows the progression of diatoms but does not halt it altogether. I scrub my tank weekly to prevent diatoms from taking over. I hate that stuff!!!

As far as sandstone goes, I do not believe it is aquarium safe. I had to look around for it but here is an article one of the Mods directed people to on the old boardâ€¦
http://www.uniquaria.com/articles/sr.html

HTH

Jayhawk · Post by **Jayhawk** » Thu Jun 16, 2005 4:12 pm

That's an interesting article, but the bubble test doesn't really work since lava rock is listed as safe and bubbles simply because it is honeycombed with little holes and retains air. Now, if a rock perpetually bubbled that'd be different!

Still, I'd err on the side of caution with sandstone since I don't know much about it.

I tell ya all, google duckweed...it's an excellect phosphate remover - lots of good scientific data on it's ability to remove phosphate and nitrates all over place. Duckweed is one well studied little plant that is absolutely harmless to fish, and it's usually free.

Eric

Post by **RTR** » Fri Jun 17, 2005 5:36 pm

Correction: Diatoms do contain chlorophyll and are very definitely photosynthetic. They do not contribute as much O2 to the atmosphere as do the BGA, but they are guesstimated to account for up to 25% of the planet's carbon fixation. As they are easily silicate-limited, they rarely out-compete green algae in tanks. They can do well in less light than the green alage and the BGA.

PhosGuard and similar resins work against diatoms because they pull the silicates out as well as the phosphates.

Jayhawk · Post by **Jayhawk** » Fri Jun 17, 2005 7:23 pm

That's interesting about diatoms being phosynthetic. I wonder if in higher light they are simply outcompeted by most plants and that is why they decrease in FW with increased light (I've never tried this in a plantless tank).

It's probably just me, but resins make me nervous. What are they? Do they leach anything else into the tank? They may be necessary with some set-ups, but if I can get plant growth I just don't have diatom issues so I usually opt for that route.

Eric

Post by **RTR** » Sat Jun 18, 2005 10:33 am

Seachem is unusually open about their products (the biggest reason other than their convenience that I use them, plus I have had a number of face-to-face sessions with the cheif scientist/owner at meetings/conventions). They can generally back up any isues that you have. Go to their site and browse around and/or email them. They are responsive, but it may not be Greg Morin himself who responds.

I have used their phosphate resin extensively without any problems, but avoid it for anything other than a few dispay tanks simply due to cost.

rainmaker69 · Post by **rainmaker69** » Sat Jun 18, 2005 10:50 am

Correct me if I am wrong but does not the water absorb different parts of the spectrum the deeper you go? So a deeper water fish would require a different spectrum than a shallow water fish?

entropy · Post by **entropy** » Sat Jun 18, 2005 12:20 pm

RTR, right you are sir. I always thought that diatoms were more protists than algae (whatever the taxonomic groups are... closer to the amimal side than the plant side) The whole "not being green" thing threw me...

Picked up some phosguard, it was pretty pricy, but this is only a 10 gallon tank so it should last for a while...

Interestingly enough on the carpet of diatoms I had on the back wall I had all these very small critters, less than a mm long, that appeared to be grazing on the stuff. they were far too small to be able to tell what kind of organism they were, but they were moving fairly rapidly.

Post by **RTR** » Sat Jun 18, 2005 7:12 pm

The beasties were likely some sort of copepod. Diatoms in SW in the plankton are caviar. The common FW and BW situation with surface-attached diatoms means that they are still prime food, but many of their grazers are also prime fish food, so we rarely have enough population for diatom control.

As an aside, Olive Nerites - if they can survive (i.e. no puffers) do a good number on diatoms.

Post by **RTR** » Sun Jun 19, 2005 12:14 am

rainmaker - yes, the red end of the spectrum is absorded fastest, the blue end penetrates deepest. This is relatively trivial for FW plants and the few BW plants as they are all shallow-water plants. In reef tanks it matters more.

All algae and other photosynthetic organisms (BGA) require light. But light does not "cause" or promote BGA. As said before, that is a water quality issue. Those bacteria are everywhere, probably the commonest photosynthetic organism on the planet, and likely one of the oldest surviving ones. Excluding them from your tank is highly impractical.

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Getting rid of diatoms in a brackish tank