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Aquarium sand and diatoms...

dcurzon

Member
Joined
4 Jul 2020
Messages
378
Location
Essex
So one of my tanks seems to be in a perpetual state of diatoms. It was converted back to fish maybe 18 months ago or so, so easy to lose track of time.
Juwel Rio 125
2x 28w T5's. These are old bulbs, probably at least 8 years. Approx 8-10hrs a day.
Eheim 2215 - Intake rear right, spray bar along left side blowing down length of tank
CO2 via fire extinguisher and inline diffuser
Tank is in the lounge, so some light source other than over the tank.

My suspicion though, is that the sand I used might cause the problem. Bought from AMAZON in the photo's, its describes the product as "chosen from selected silicate aggregates blah blah"

I'm just in process of building a full-length spray bar to span the back to see if that helps at all, having just cleaned up every surface within again. Plants seem to struggle to grow in this tank, although I have some Java ferns that seem to be doing 'ok'.
 
Im guessing the silicate sand is the problem. Im not sure if rinsing the sand does anything. I have read a post here somewhere saying silicate in the aquarium is not a trigger for diatoms so dont know. Maybe the connection between silicate, and diatoms is sending people down the wrong path.
 
Almost all inert aquarium sand is silica. Its not available to diatoms in this form.
@dw1305 knows more about it
Hi @Hufsa

If I remember rightly, the element silicon is available to diatoms but I can't remember the chemistry involved in this process. @dw1305 and I discussed this in a thread somewhere here on UKAPS. If I get a moment, I'll search for it. It took me by surprise when we made this discovery.

JPC
 
Im guessing the silicate sand is the problem
My suspicion though, is that the sand I used might cause the problem.

As mentioned above, neither sand nor silicates in the water column have anything to do with diatomic algae.
Troubleshooting has to begin with the basics such as review of lighting, CO2 and flow/distribution.
Did the issue arise 18 months ago? What is the gas/light schedule, etc. etc.

Cheers,
 
Cheers all...
Yes, diatoms since a couple of weeks into startup (as one would expect), and has been constant since.
Actually a review of timelines and its nearer 12 months than 18. Lockdown stir crazy.
I bought the tank 2nd hand, originally to house a rainbow crab. The crab was in there for approx 8 years. Diatoms were never an issue whilst used as a crab home, as they are land crabs so it was partially filled 50/50 land/water areas.

With that in mind, I've never changed the T5's that are in it.
Stock Juwel 2x28w T5's.
Lighting runs between 8-10 hours/day (because sometimes I'll put it on for an extra hour or 2 at night for viewing)
lights on/off: 12pm - 8pm
co2 on/off: 9am/3pm
co2 delivery: Inline diffuser to spraybar
I've recently removed a lot of plants for tank cleaning, with a replant when I feel the diatoms are a little more under control. So I've dialled the co2 down a bit in the interim,

Next steps:
So I need to make changes, watch, wait and see...
Flow
Spraybar was at one end, flowing the length of the tank. What I noticed is that whilst the flow did reach and circulate, lots of crud ended up in the area below the spraybar. which was a bit of a dead spot. Im experimenting with building a long spray bar to run along the back wall. v1 was the Eheim extendable. Too many holes = not enough pressure. v2 is DIY, and much better, and the flow circulates front to back quite well. However, holes are bigger than they need be, so v3 will be when I find a smaller drill bit :)

Light
So I could replace the tired old T5's. But I have my eyes on a few LED items on Ebay. Light definitely also needs addressing.
 
Hi all,
Get some Ramshorn snails they will eat diatoms off everything!
I'm a snail fan as well.
Maybe the connection between silicate, and diatoms is sending people down the wrong path.
Yes, I think it is a case of 2 + 2 = 5.

Sand, glass, quartz and diatoms frustules are all made from silicon dioxide (SiO2), but so are some of the <"oldest rocks on earth">, and that is because it is very hard and <"totally insoluble in water">.

I think of silicon dioxide (SiO2) as a bit like the nitrogen (N2) gas in the atmosphere, you <"can't equate N2 gas with nitrate (NO3)"> and you can't equate SiO2 with silicon.

<"Diatoms are incredibly efficient"> at extracting silicon (Si) from solution, but that silicon has to be in the form of <"orthosilicic acids (H4SiO4)">.
..... Diatoms are photosynthesising algae, they have a siliceous skeleton (frustule) and are found in almost every aquatic environment including fresh and marine waters, soils, in fact almost anywhere moist......

cheers Darrel
 
Get some Ramshorn snails they will eat diatoms off everything!
unfortunately clean up crew (snails/shrimp) wasn't really an option - tiger barbs and yoyo loach... However, yoyo loach seems to have vanished without a trace, which makes snails a possibility now. Also wondering about some otto's unless the barbs will bother them too much
 
As mentioned above, neither sand nor silicates in the water column have anything to do with diatomic algae.
Hi @ceg4048

To what are you specifically referring when you say "As mentioned above..."? I take your point that sand and silicates may have nothing to do with growth of diatoms. But, that being the case, what then causes growth of diatoms?

JPC
 
I'm going with @Geoffrey Rea 's suggestion to just replace the sand periodically. Regularly turns brown or greenish for me as well :) If that is the only thing not going entirely according to your wishes, but plants and fish are thriving, I wouldnt change too much.
 
Hi @GHNelson

That may be correct but I find that Ramshorn Snails take over the tank and become a major problem in their own right. Perhaps you have mastered a method for controlling their population growth? If so, what's the secret?

JPC
Haven't got fish..... so not any uneaten food to scavenge!
 
As mentioned above, neither sand nor silicates in the water column have anything to do with diatomic algae.
Hi @ceg4048

I thought I should re-visit this and found the following:


From the above link, I have extracted this:

"Studies of temperate-zone lakes have shown that diatoms often bloom in the spring, but this phenomenon leads to reduced silica concentration. Once the silica concentration declines, other types of phytoplankton that do not need silicon typically replace diatoms as the predominant form of planktonic algae".

The above quote and the article itself leads me again to the conclusion that diatoms and silicates are indeed correlated.

JPC
 
unfortunately clean up crew (snails/shrimp) wasn't really an option - tiger barbs and yoyo loach... However, yoyo loach seems to have vanished without a trace, which makes snails a possibility now. Also wondering about some otto's unless the barbs will bother them too much

I was going to suggest Oto's - they do require specific care, but they can clean a tank of diatoms in matter of days.
 
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