# "Dust" algae normal?



## trenac (Feb 15, 2004)

Yes, I get this haze on my glass between water changes and do not consider it an algae problem, I assume/consider it is normal accurance. I consider a algae problem as a out of control situation that covers plants, decor and cannot be controlled with just cleaning.


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## Troy McClure (Feb 22, 2004)

Sorry to bring this post back from the dead, but I can't seem to keep the green dust algae off the glass. It's not the bright green hard spots that grow on anubias leaves and in patches on the glass...it's more of a dull green dust over the entire pane. The stuff comes right back a couple days after I clean it off. I've even been wiping the glass down with a paper towel when the water level is down during WCs. Ferts stay constant, NO3 ~10ppm, PO4 ~2ppm. Macros dosed on S and T days, micros on MWF. Lighting is 1x36W and 2x13W over a standard 10gal. Photoperiod is noon to 10pm.

Oy...this is the only algae I have. I guess I can still be thankful for that...


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## motifone (Nov 21, 2004)

Troy,

Yes, my dust typically returns gradually about 3 days after a glass cleaning. I have an acrylic tank and wipe the glass with a pad during tank cleaning. Midweek, I have started using a magnetic algae cleaner -- as a means of polishing the acrylic again without having to get my hand and arm soaked again.

It' s really only visible from a few feet away, but does reduce the viewing pleasure if you are a nitpick like me . I tend to think most folks get the dust, especially those running more wattage. Me, I run 192 watts of CF.


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## Troy McClure (Feb 22, 2004)

I suppose I would run the floatmag across the glass during my morning fert dosing, but I'd rather eliminate the cause. I don't like using the floatmag because then all that algae is floating around in the tank....


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## trenac (Feb 15, 2004)

Troy... Try decreasing N03 and see what happens. 

About a month ago I started increasing my N03 and started getting a bright green algae covering my glass. I could scrape it off and within 3-4 hours the glass was covered in the algae again. The algae got so thick you could hardly see inside the tank. So I cut back the N03 and within a week the green algae was gone and has not returned.


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## Troy McClure (Feb 22, 2004)

For a week now I've been adding 6ppm NO3 and 2ppm PO4. I've been adding that much on S days and T days. So it'd be Sunday +6/2, minus uptake (whatever that is,) Tuesday +6/2, minus uptake, etc., etc. Plants have been growing like crazy. Maybe I'll cut it back to 6pm/2ppm on WC day, then less for the rest of the week, starting with half. If in three weeks I don't notice a change...I'll resurrect this thread yet again.


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## Troy McClure (Feb 22, 2004)

Quick update - It's now the end of the week and the 'dust algae' is just now showing itself on the glass. Seems that I've got this problems licked and all I did was cut down on nitrates. Thanks for the help!


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## motifone (Nov 21, 2004)

Troy

Interesting. I am going to try to reduce my nitrates as well. I don't remember having to wipe my glass every day/every other day. I suspect because I have cut down on the number of plants in my tank, I don't need as much nitrates.

Do you follow the Tom Barr method of dosing? It seems like your method is slightly different because you take into account uptake. In other words, with Tom's method you would be tossing a full 6ppm of nitrates into the tank everytime you dose. But, with you, it sounds like you are estimating or measuring uptake and only dosing for the difference to top things up to 6ppm. Like, on dosing day, you tested your water and it read 4ppm, so you would dose 2ppm.

Just curious


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## Troy McClure (Feb 22, 2004)

It seems that I have siked myself out. I didn't actually get rid of the dust algae on the glass. Here's the kicker though: In my 85gal that isn't totally set up yet, I have no CO2 and only dose NO3 and PO4. No dust algae. In my 10gal, I have all the bells and whistles. Dust algae that returns within a few days. My NO3/PO4 dosings have been 3ppm/2ppm on S-days and T-days. .5ml Plantex and .5ml Iron MWF.


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## Wasserpest (Jun 12, 2003)

I noticed a similar relation between nitrate levels and green algae on glass (and plant leaves).

Usually I keep my NO3 around 5ppm, but over the last few weeks I got them up to about 20ppm and this is how it looked like:










This was how it looked like after two days  

It's much better now... :fish:


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## shalu (Jan 16, 2003)

my nitrate was in 60ppm range, still no algae on glass. The thing that made most of my glass algae(dust and spot) disappear is high PO4 dosing.


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## Troy McClure (Feb 22, 2004)

How high? I don't think my PO4 drops below 2ppm.


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## Wasserpest (Jun 12, 2003)

Keep in mind each tank is different, and while one is absolutely algae clean with whatever you throw at it, another one might react fiercely... YMMV as always. :fish:


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## shalu (Jan 16, 2003)

My dosing is way beyond what is 'necessary', 3ppm PO4 every other day.


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## plantbrain (Dec 15, 2003)

trenac said:


> Troy... Try decreasing N03 and see what happens.
> 
> About a month ago I started increasing my N03 and started getting a bright green algae covering my glass. I could scrape it off and within 3-4 hours the glass was covered in the algae again. The algae got so thick you could hardly see inside the tank. So I cut back the N03 and within a week the green algae was gone and has not returned.


If it grows back in 3-4 hours, do you really and honestly think is has anything to do with nutrients?

No algae grows that fast in our tanks.........
3 days? sure, but 3 hours or less.

They are zoospores, they can swim.
You scrub them off, they swim back and reattach.

You can scrub them off and immediately do a large water change and or run a diatom/UV.

You can also do daily scrub/water changes and theat will reduce them way down, then do a blackout for a couple of days and scrub.

They seem to go away on their own with reduced light also.
I have no issues with this alga at all sorts of dosing routines, but 36w+26w on a 10 gal tank is asking for it.......

Also:
Pull the light away from the front of the glass, unless there are plants there, why light that part?

You can try the less NO3, as long as you do not bottom it out and stunt the plants. May as well dose less everything also.

I've never been able to keep for longer than 3-4 weeks and still don't know how to induce it.

The resistent spores are certainly present in my tanks, I've inoculated a dozen or more times with only 3 successes of which most were weekly only.

Regards, 
Tom Barr


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## Troy McClure (Feb 22, 2004)

My hood is set up like this:

```
back
--------------------
| ================ |
| ================ |
|                  |
| =======  ======= |
| =======  ======= |
--------------------
front
```
I'll take the front 2x13s out and see if that helps. It would be a real pain to move that 36W to the center of the hood, certainly not impossible though.

Good thing Tom mentioned it, my 85gal also has a UV sterilizer. That's probably killing any spores in there while the spores in the 10gal are thriving.


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## motifone (Nov 21, 2004)

I will chime in here.

Since reducing my NO3 and PO4 -- actually, since stopping artificially fertilizing both -- the dust algae on my glass has declined dramatically. Week ago, I had to wipe the glass of a slight film at the end of every day. Now, since reducing my NO3 and PO4, I can go several days before it really becomes noticeable. I also no longer get green spot on my Pennywort.

Careful. I am not advocating stopping ferts. It just so happens that have have enough fish in my tank and I feed them frequently enough to keep my NO3 and PO4 levels sufficiently high without bottoming out. The levels are high enough without supplemental dosing -- the supplemental doses I was adding before were contributing to needlessly high levels of ferts in the tank.


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