Thread & Stag Algae - High Phosphate?

[Tonyb111111]

Hi all, I am having real problems with the above two algae's. I have a 200 litre planted tropical, do weekly 15% PWC and zero ammonia, nitrite and 10 nitrate. I have just purchased a phosphate test to see if I had high results causing the algae, and was shocked to get a result of 3ppm. I realise that this may be due to over feeding and have since cut feeding by half. I should also mention that I have twin 39 watt T5 lights on for 9 hrs a day. This was originally 12 hrs a day, but as the plants were going mad and algae was starting to show I have gradually cut it back, this appears to have made the problem worse and I am now thinking about going back to 12 hrs a day again. I think that the high phosphate is the reason for the algae, and would like to reduce this as quickly as possible , a 50% PWC done yesterday has made no difference at all. As anyone got any ideas on how I can reduce this quickly, I am currently removing with a toothbrush.
Thanks

 

[DrRob]

Have you checked the water source that you're doing water changes from?

 

[SO19Firearms]

We know Phosphate doesn't cause algae so we can rule that out, but you did give some clues to the problem -

I should also mention that I have twin 39 watt T5 lights on for 9 hrs a day [...] This was originally 12 hrs a day, but as the plants were going mad and algae was starting to show I have gradually cut it back

From that we can guess that your massive photo-period was (and probably still is) running your plants faster than the CO2 levels in the tank can sustain - resulting in low co2 and staghorn...probably

I'm guessing you don't add ferts or dose EI, but the info in this guide will help you out. Reducing your light would be the best start IMO
The planted tank - Algae guide

 

[ZoddyZod]

moved this to the Algae section.

 

[Tonyb111111]

Have you checked the water source that you're doing water changes from?

Hi DrRob, unfortunately the tap water is high at 2.5ppm. Original aquarium fill was with tap water, weekly PWC has been with RO as the tap water was 14 GH and 8pH. Tank is now too low at 5 GH and 6.2pH. So I would like to change to alternating weekly PWC of tap and RO to raise these two parameters, but this will introduce more phosphate. Do you think I will need to control the phosphate chemically?

 

[Tonyb111111]

We know Phosphate doesn't cause algae so we can rule that out, but you did give some clues to the problem -

I should also mention that I have twin 39 watt T5 lights on for 9 hrs a day [...] This was originally 12 hrs a day, but as the plants were going mad and algae was starting to show I have gradually cut it back

From that we can guess that your massive photo-period was (and probably still is) running your plants faster than the CO2 levels in the tank can sustain - resulting in low co2 and staghorn...probably

I'm guessing you don't add ferts or dose EI, but the info in this guide will help you out. Reducing your light would be the best start IMO
The planted tank - Algae guide

Hi, I add 20ml Easylife profito fert every week. I will cut back the lighting to 7hrs per day and maintain low intensity moon lights for evenings. Do you think I will have to go down the CO2 route to get rid of this problem?

 

[SO19Firearms]

Do you think I will have to go down the CO2 route to get rid of this problem?

Not if you maintain a low-light environment, you'll probably have to tackle the algae at hand tho.
Easycarbo could be an alternative to CO2

 

[Tonyb111111]

Thanks for the advice, in summary then reduce the lighting and add liquid carbon and see what happens. What does high phosphate affect?

 

[SO19Firearms]

Thanks for the advice, in summary then reduce the lighting and add liquid carbon and see what happens. What does high phosphate affect?

Nothing. In a planted tank high nutrients don't affect anything. Lack of nutrients affect stuff tho...

IMO