Originally Posted By: Martin-dive
Hi. Im starting this personal project. It is a quarry, 600X900 feets (size). max deph is around 30 feets.
My goal is to get better visibilitu in the water.
There are few fishes, almost no acuatic vegetation. P levels are somehow high (water analisis shoews P are below permitd levels but not far from limit).
At the beginig water was somehow clear, like 30 ffets clear. But that was at the surface and till 15/20 feets deep. From there the water was reaaly dark, and witha strong sulphur smell.
reading information (there is no pro help here available) in this forum, I started with the idea of areation. I mounted a compresor and an air difuser, 30 feets deep (my calculations were to install 5 of this areators, I started with 1 for testing purposes). The water moved by the aereator is reaaly impresive. The water comeing from the bottom was really "smelly", a very strong sulphur smell came up, thatwas for the first week, then the smell was decreasing. After 2 weeks the smell desapeared, completly. The dark water in the bottom desapeared. But at this time the water turned green, really green. Water clarity decreased to only 1 feet. The bottom now is in dark: no light reaches the bottom (is filtered in the first 2 meters of the water column).
almost 2 moths has passsed and not improvements in ewater clarity.
I know Im haveing an algae bloom.
I have added benefical bacteria.
Now Im planning to use Aluminium sulphate to deny P to the algae. What do you think about it, can you tell me how do I calculate the amount of alumiun sulphate I need?
I have done tests on bottles: the water turns milky, and a cludy water forms.
Here it is some data of the water analisis:
PH: 6.6
CO3CA 266
Phosphates 1,8 mg/l
S 0.95 mg/l
Disolved O2 7.2 ppm
DBO 122
CACO3 203 mg/l
NO3- <5
NO2- 0.01
SO4= 103 mg/l

I know that in a long term , to control phosphates I should have acuitic plants? Im in that way, but for the moment I need to control this algae bloom.
Thanks for the help and advices


To bind P with Alum into Aluminum Phosphate, apply at least 250 pounds (22.7kg) per acre/foot of water Use Hydrated lime at a rate of 50% of the alum used to keep your pH balanced, but do NOT mix the alum and Hydrated lime in the same mixing container.

Applying the Hydrated Lime first will also kill much of the algae bloom before the alum binds the P, and flocculates the solids