GDA: observations from a client tank

[Tom Barr]

The recent redo of a 350 Gallon tank has often led to many good test to see, even if "mistakes".

The initial bloom about 3-4 weeks into the reworking of the tank= GDA bloom. A few extra water changes and cleaning, it was gone and did not return.

Well, till I came in today.

I looked under and what did I see?

Empty CO2, look like the tank had been empty for a few days. Light was low, about 40 umols, so it was not a serious case.
Switched the tanks out, cleaned things up, Swapped the canister filter(it was clogged as well) with a newer larger pore media, trimmed and when I go back the next week, do you think I'll see GDA again?
Why/why not?

What does this imply?
Autodosing, plant biomass was also pretty high, I did not trim last week. Light was/is the same. Filter clogging is one variable in addition to CO2........

Filter clogging (canister is an entirely separate and independent filter system vs the main wet/dry filter) and CO2 running out are the two main variables.
I've seen this in the past with BBA. I addressed this BBA by adding some Excel to the autodosers. So the plants still have some Carbon backup, so "poor poor growth" is not a factor, nor BBA which is much more annoying to me.

I've noted this before also about moderate/temporary to poor CO2 being the cause for various green algae and really bad chronic CO2: BBA issues.
We might say the canister filter was removing the GDA until it clogged. But prior? The Canister was taken off line for 2 weeks as it kept clogging. No GDA, so there was a control for the canister. We know Excel will do nothing to GDA.

 

[Matt F.]

Tom, the only time excel seems to do anything is when it is dosed directly onto hardscape items that are out of the water, or just beneath. This allows the glut to sit in full concentration directly on the GDA. Usually within a day or two, the green on the rock is gone. along with the BBA!

dosing excel via water column does little if anything to inhibit GDA growth.

 

[Tom Barr]

dosing excel via water column does little if anything to inhibit GDA growth.

Yes, agreed, my experience as well and the test I did is also supportive of that. Excel dosing alone did nothing to slow or stop it from what I saw.
Excel might help prevent the BBA some and help the plants grow okay till the CO2 tank gets swapped out later the next visit I come by to check(client does not do that at all here).

 

[Matt F.]

This GDA has me so confused! I started dosing my tank with the normal ferts (gh, kno3, khpo4, and csm+B), but at reduced rates. Actually I've halfed most of the Ei doses and quartered the kh2po4, so Po4 is limited. I've also added glut again at the recommended levels (not double dosing).6 hour photoperiod. GDA likes low flow and high flow as well. I wish I could induce a GDA outbreak. If I'm not able to induce the GDA, we might have to face that fact that GDA is a seasonal algae?

Your client's tank was lacking in upkeep, so algae blooms aren't a suprise. It was prob like when I get home from a week or two vacation...lol Sounds like it could have been worse if the lighting was more intense!

Also interesting is the fact that the GDA grew with a fair amount of plant biomass. I've had GDA in tanks with a lot of biomass. The first shot of my tank (in teh other thread) even had some GDA near the substrate, iirc.

 

[Tom Barr]

Yea, but CO2 still seems to be the main throttle to get the GDA going. I've seen little else that can do it.

The fix will be realized once I go again next week.

 

[Matt F.]

Yea, but CO2 still seems to be the main throttle to get the GDA going. I've seen little else that can do it.

The fix will be realized once I go again next week.

This very well could be the case. I was injecting 2-3x the amount of CO2 in my 60P when I had my GDA problem. When we spoke the last time, My lily pipe was rippling the surface of the water in the tank (this would get worse as the water evaporated). I can only guess that the co2 level was fluctuating wildly. Had BBA, etc. Since lower the outflow, I've been able to reduce the amount of CO2 I inject, and I've had no BBA. The GDA hasn't come back, either...

Keep us posted.

 

[Tom Barr]

Yea, but BBA is easy to kill off, GDA is not so easy.

The cleint's tank also got BBA, but.........it stopped dead in it's tracks after the c/O2 was corrected. This latest case, there was no BBA bloom.
I guess the shorter CO2 issue was not enough to induce BBA, but enough to induce some GDA.

That's generally the pattern also: Milder CO2 issues: Hair algae/GDA/GSA/Caldophora
More serious CO2 issues: BBA.
CO2 plus organic loading: Green water and Staghorn.