Algae id and possible cause ?


New Member
25 May 2020
Lake Havasu city, Arizona
Need help with my wife’s parents tank.

40g breeder l
Ehiem canister
Fresh and plant 3.0 led fixture
25% percent water change every week
Dosing excel once right after the water change
Dosing potassium once after water change
Dosing flourish once after change.
3pm to 9pm light schedule...

that’s the schedule for the tank.

any ideas? Thanks!


15 Jan 2020
It looks like there is a lots of floating dirt in the water column, most probably from decaying plant matter, it also covers your plants and it's a very good foundation for staghorn-like algae.

Looks that you dose only tiny amounts of N and P (not sure how much K, generally we may need more detailed info about your dosing regime, water parameters etc).

If it was my tank, I'd clean everything thoroughly removing as much of affected/dead plant matter as I can, dose Excel daily, dose Flourish every other day, but most importantly start to dose P (dosed next day after Flourish), N, K and Mg.

There are of course many dosing regimes/styles, but it's a low tech with no gaseous CO2 so I'd start at approx 5-10ppm of NO3 weekly, 1-2ppm of PO4, 8-10ppm of K and 3-6ppm of Mg (amount of Mg would depend on amount of Ca you have in the water and you should start to dose from lower amounts of ferts and increase them over couple of weeks while your plant mass will increase). There is a chance you may have outbreak of other, mainly green types of algae as plants will need to reprogram their enzymes to different amounts of ferts, but after 2-3 months everything should be ok. And keep proper weekly maintenance (cleaning etc.)
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