# still got diatom algae



## misscaretaker (13 Nov 2008)

Hi, my tank has been set up for 3 months now and I still have diatom algae. I thought this was only meant to last a few weeks  . The specs are: 210l, 2x36w T8 lights on for 8 hrs, fluval 405 filter (already matured), FE CO2, dosing TPN+ . It's fairly heavily planted and not too heavily stocked (I don't think so anyway!).The occupants are: 5 (was 6) ottos, 2 angels, 2 plecs, 2 clown loach, 6 red-eyed tetra, 3 peppered cory and 3 panda cory. Oh, not forgetting the MTS and 3 Apple snails! I have another filter - eheim 2026 - which just needs some media which I was going to put in aswell as the 405.
Just noticed that the vallis has fuzzy edges and the java moss has algae in it...


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## aaronnorth (13 Nov 2008)

It takes a few months, are you still getting as much as you used to or is it starting to slow down?

If you have silicates in your water then it may never go.


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## misscaretaker (13 Nov 2008)

It is starting to slow a bit, but everything's still rather brown! As for silicates, the sand in the foreground is from a spare bag the bloke I bought the tank from gave me so I've no idea unfortunately.


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## scottturnbull (13 Nov 2008)

The best way to control hair on vallis is by pruning. Trace the affected leaf-strand down to the bottom and strip it away from the crown.


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## ceg4048 (14 Nov 2008)

aaronnorth said:
			
		

> If you have silicates in your water then it may never go.


It continues to astound me that we perpetuate this theory without any proof or without even questioning why this should be.

Think about this for a moment: Popular aquarium sediments are constructed of inorganic silicate compounds. Clay, such as Aquasoil is a type of "Phyllosilicates" constructed of aluminum/silicon/oxygen molecule arranged in parallel sheets. Sand is typically made of quartz which in the family of "Tectosillicates" and is also an aluminum/silicon/oxygen molecule but arranged in geometric lattice. Quartz is one of the harder substances known. It actually ranks slightly higher in hardness than steel. There is about as much likelihood that the silicate molecule will leach into the water column from quartz sand as would the silicon dioxide molecule of which your tank's glass is made of would. So in effect silicates in the tank never go away as long as you have glass, clay or sand in the tank yet diatom algae is not currently present in all those tanks. I can add kilos of sand to my tank and this will not spark a diatom algal bloom - so this theory must be either false or incomplete.

While it is true that Diatom algae use silica to build their cell walls (known as frustules) the origin of the silica from diatoms in an aquarium has not really been verified. Their uptake of silica must be in the form of the various forms of silicic acids such as H2SiO3. This can only occur by chemical reaction of silicate salts present in the water column. It is more likely that these salts are either in the tap water or are leached from the plants themselves due to poor nutrition. Plants uptake silica salts as well and in terrestrial plants the silica is used to strengthen the cell walls to toughen it against pest attack ( as demonstrated in this paper ). The salts are made available by the reaction of humic acids in the soil with any available silica salts to form silicic acids.

Still, the presence of silica salts in the water column by itself does not induce diatom blooms. This is a false correlation. Something else induces the algae which then feeds on whatever is available in the environment. There is a greater probability that the issue is poor nutrition, principally poor CO2 or poor CO2 distribution, as the OP reports algae on the leaves. Blaming excess silicates for diatom algae is about as unreasonable as blaming excess nitrates for BGA.

I would increase the frequency of large water changes, remove by hand, add more flow (or rearrange the piping) and carefully increase the injection rate.

Cheers,


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## aaronnorth (14 Nov 2008)

So what causes diatoms then? Just the immature tank itslef that is still creating bacteria/ NH3 presence?


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## misscaretaker (14 Nov 2008)

How on earth do you know all this?   I must say that I always have to read your posts 3 or four times before it all makes sense! You must have a scientific background or job 'cos you _really_ know your stuff!

The tank is 4' long and I am planning to put another CO2 diffuser at the other side of the tank as well as adding another filter this w/e, so hopefully that will help. I do approx 30% water change every week, so I'll up that to 50%  (at least I'll be used to that when I start dosing EI, which I hope to do soon!).


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## ceg4048 (14 Nov 2008)

aaronnorth said:
			
		

> So what causes diatoms then? Just the immature tank itslef that is still creating bacteria/ NH3 presence?


Unfortunately we really don't know all the factors yet, but certainly light is one factor because I've been able to curtail it by light restriction and via blackouts. I'm also of the opinion that ammonia is a factor, which is a heck of a lot more prevalent in the water column of a new tank than silicates are, that's for sure. I reckon it's some combination of light, ammonia and low or unstable CO2. Perhaps this species is quicker to respond to these conditions than other forms. It may also be related to some "life cycle" process like GDA is, but there is a global mind set against silicates so no one bothers to investigate further.  Remember when it was widely assumed that hair algae was caused by excess Fe simply because analysis of the follicles revealed that hair algae was high in Iron? It was only after repeatedly increasing Fe levels without inducement that it was demonstrated that it couldn't be Fe related, and in fact it now shows high correlation to poor CO2.

As Jo mentioned, diatoms are supposed to go away after a while but once induced, no algae will have a reason to go away if conditions are favourable to it's continued growth. What surprises me though is that Jo's lighting doesn't seem unreasonable at all, 72 watts T8 over a 50 gallon shouldn't be a problem, so next on the list nutrient/CO2 stress due to either low levels and/or low flow. It appears Jo that you have plans to address these issues. Definitely do more frequent and larger water changes but don't forget to dose after the water change...

Cheers,

PS read, read, read, read, read and then when you're done, read some more...


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## scottturnbull (15 Nov 2008)

A UV steriliser might be a good short term fix. Once the plants establish themselves diatoms shouldn't be able to get a foothold. Like ceg4048 says, plants can utilise silicates. In fact, they can use silicates at an astounding rate. (In the past, I've used potassium silicate as PH up with Hydroponics.) Instinct tells me the diatoms gained a foothold while your plants were still acclimatising. Now they have the upper hand, the plants are suffering, and the diatoms aren't going away. I'd heavily prune affected areas, and run a UV steriliser until the diatoms are in retreat. After that, with vigorous plant growth, they should stay marginalised.

I had diatoms in my own tank recently, although not to the extent where I could see them with the naked eye. They showed up in a drop smear under the microscope. I added some lead-weight plants my LFS had on offer, which triggered an explosion of bacteria. (The plants were lying horizontal in the shop, more or less rotting.) I've been running a UV sterliser for a couple of weeks since then. Diatoms are now almost completely absent from drop smears, and the bacterial population has narrowed down to usual levels. If only the snails would make their way, in good order, through the UV steriliser, my happiness would then be complete.

On a hunch that decaying plant material might be a factor, I just did a google search. I found this article (scroll down, past the section on REM sleep). Here's a quote (the emphasis is my own):


> Traditionally, earth scientists have believed that the amount of silicon found in water â€” in streams or in water trapped in soil â€” depends upon the rate at which rocks weather and release silicon from minerals. In fact, scientists have used measurements of silicon concentration in streams to derive weathering rates for rocks in the vicinity. In the ocean, on the contrary, the evidence points to plants, or plankton, as the dominant players in silicon processing. Silicon levels in the water are low at the surface, where plankton are alive and active, _and high at the bottom, where decaying plants release their silicon into the water._


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## misscaretaker (15 Nov 2008)

If I had a UV sterilizer lying around, I'd say that's a great plan! Unfortunately, I don't have one and my overdraft tells me not to buy one!  The worst affected plants are the swords as I said before but at least the angels are really cleaning one of the leaves now getting it ready for spawning soI can't even get in there to wipe it off  . I didn't get a chance to do any water changes last w/e as we had a funeral saturday (6 hour drive  )and my dad's 60th birthday sunday, so I was too knackered which hasn't helped. I'm going to try for a 70% w/c tonight and really clean everything prior to putting the new filter on tomorrrow.


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