green spot algae

[illumnae]

is there any particular cause to this form of algae, or is it something that every aquarist just has to resign himself to?

[PeterGwee]

Low PO4, poor CO2 during the photoperiod or both.

Regards,
Peter Gwee

[illumnae]

hmm ok thanks for the info

i've been dosing recommended doses of PO4 based on the EI guide (1/2 teaspoon 3 times a week) and based on Chuck's calculator i have too high a ppm of PO4 every dosage (this dosage gives me 3.99ppm per dose).

CO2 wise i think it should be sufficient as well as before the fish were added, the plants were bubbling like crazy, and even now that the fish are in i'm seeing great growth in all the plants

could it be that the added NO3 from fish waste/fish food and added CO2 given by the fish respiring is causing even the large amounts of PO4 dosed via EI to be depleted quickly?

[PeterGwee]

No. It is a CO2 issue definitely then since the dosing of PO4 rules it out as a factor. Unless you mis-indentified green dust as green spot algae, it is definitely a CO2 issue. Try getting a drop checker with reference KH solution of 4. Get a pH of 6.6 with the correct intensity of green for the drop checker with that reference KH of 4. Take a sample of the tank water and leave it for 24 hrs. Measure the pH and take the pH of the tank water after the CO2 is turned on for an hour or so. It should have drop by 1.0 or close or else you likely need to improve the system by adding more flow through the tank or reactor (more flow pass diffuser).

Regards,
Peter Gwee

[illumnae]

i've got a drop checker showing between 6.6 and 6.4 ph with a KH4 reference solution, and some of the larger fish gasp for air if i increase CO2.

i'll try the ph method tomorrow

[PeterGwee]

i've got a drop checker showing between 6.6 and 6.4 ph with a KH4 reference solution, and some of the larger fish gasp for air if i increase CO2.

i'll try the ph method tomorrow

Increase the surface movement some and make sure you have good circulation of the tank water and good flow through the reactor. Getting the CO2 rich water well mixed is key. You likely have response issues with your CO2 system. Do the pH method to test the responsiveness of your CO2 system.

Regards,
Peter Gwee

[wasabi8888]

illumnae

Let us know the results of the above. I am interested to find out.

Peter

I always have problems differentiating green dust and green spot. How to I spot the difference?