Bert H

I am guessing here, but it would stand to reason that once the spores have gone their life cycle, they will then revert to a dormant phase, until something triggers them to start the process over again.

hoppycalif

Green dust algae on the glass is an algae still in the zoospore stage, meaning it is a free swimming algae that is extremely robust. All algal spores are able to survive almost anything from boiling to freezing to drying out. So, when we clean off the GDA the spores left in the water, and there are always some left, just swim around and find the nice smooth glass again, where they again stop and start a new bloom. But, the adult stage of this algae is not nearly as robust, and is not free swimming. So, letting it complete its life cycle to the adult stage lets us have a very much improved chance to kill it off. I assume the adult algae releases sporess again before it dies, but until something triggers those to start the cycle over again the tank is free of that algae. This is, I think, how Tom Barr explained it. The only part that confuses me is why the stuff never seems to start over again from the newly released zoospores.

My tank is now two days into the post-scrape period. The glass seems to be getting a bit cloudy again - bad news. I plan to do another water change today and wipe it down good.

hoppycalif

Later today I checked my "cloudy" tank glass more closely - it is definitely the GDA starting over again. Not welcome news. But, I suspect I know why it has returned. A week ago I did my routine water change, but the siphon rubbed a bit on the inside of the glass at one point. When I got done I noticed there was a 3 or 4 square inch of clear glass there, right at the top of the tank, at the water line almost. I think that was the equivalent of scraping off the GDA too soon, so the spores just reestablished their growth and it blended in with the older algae. When I scraped it all off two days ago, I was scraping both old algae and young algae. Now the young apparently swam around and recolonized the glass. If I am correct, we need to treat the stuff like a newborn baby - no touchy, no feely, and definitely no scrapee!

I was too busy today to clean the glass and do a water change, so I plan to try again tomorrow. Do tears adversely affect the fish?

Bert H

Oh, no, Hoppy! I'm keeping my fingers crossed - so far, I don't see anything on the glass.

banderbe

Or why it doesn't start over again from the spores that are naturally in the air we are breathing.

That's how we get the GDA in the first place.. seems to me it would just settle out of the air, into the water, and start growing just like always.

Only thing I could think up was that maybe the adult stage leaves behind a marker that tells new spores not to grow there.. sort of an evolutionary advantage to encourage ever-greater geographic dispersal. Of course I'm totally speculating and I am not a biologist or a scientist unless you count computer science!

Who knows but if it works it works.. we shall see!

nasfish

Hi,

Finally, after weeks, looking at that ugly green mess, I cleaned it on Monday, with almost 80% water change. A lot of works, using sponge and some razor blade, like weeks of works, done in couple of hours. On Tuesday, do another 50% water change after another cleaning (even though the tank looks clean), Wednesday, another 25% water change and today, everything is crystal clear. Hope the GDA won't come back. Keeping my fingers crossed.

Best Regards

hoppycalif

I'm starting a second three week try at letting the GDA go thru its life cycle. This time I will totally neglect the tank except for light, ferts, and topping off the water. I'm now pretty sure my first attempt failed because I accidentally scraped some of it off with the siphon tube during a water change. That portion of the glass regrew more algae, but it would have remained at the zoospore level for the week before I finally scraped the whole glass, and those little beauties then recolonized the glass. Has anyone else noticed that GDA can have another more appropriate meaning than green dust algae?

upikabu

Well, here's another failed attempt at tackling GDA after supposedly letting it go through its lifecycle (at least my assumption). I let the tank go for 14 days without wiping the glass (the green dust turned into a gooey-looking mess). Last Sunday I proceeded to wiped the mess using a sponge while doing a water change, trying my best to contain the mess in the sponge. I guess I didn't succeed as 2 days later a thin layer of green dust started to accumulate on the glass again.

Maybe I didn't let it go long enough. I wonder if running a quick filter attached to the powerhead during glass wiping would help in trapping the free spores and reducing them from the water column?

nasfish

Same thing here. After two days, GDA starts to appear again. I let the tank go for about 18 days. But this time round, GDA not as thick as before. Right now, I am starting a second try, maybe leave it alone a little bit longer.

Thanks

Bert H

Follow up - well, it didn't go away completely. Actually, it is improved by about 50%. The film which re-formed was only about half of what I was dealing with weekly before. It will have to take a backseat to other stuff I have going on currently. High school graduation party this wkd and I am under strict orders that the tanks have to look good. Where I might have messed up is in not having cleaned out the filter when I did the scraping. Oh, well, the saga continues...