RO or CO2?

at the moment I am having issues with cyano in two tanks,
one has a high flow and it well planted the other is lower flow but also well planted,
I have had my water tested for silicates (trace amount) and phosphate (0.25ppm)
my other levels are
ammonia 0ppm
nitrite 0ppm
nitrate 20ppm average
now having a chat with the guys in my lfs we came to the conclusion that even though I have relatively low levels of silica and phosphate the pair together may be why I am getting so many issues with cyano,
the ideas I have at the moment are either CO2 (thought being add co2 plants grow better and out compete the cyano)
or an RO unit, the ro unit removing every thing from the water for all three tanks alowing me much more control over what's actually being added in my water so I can add ferts to help the plants but restrict what the cyano is feeding off (plus no need to dechlorinate etc etc)

so really I just wanted some opinions or thoughts from anyone who has experience of these issues or a better understanding than I have cause I am unsure what way to go at the moment
cheers.

 

I think you should dose some Fluorish Excel. Also keep your lights off for 3 - 5 days. Some fast growing plants like najas or floating plants (frogbit, duckweed) will help outcompete the cyano.

 

Common Causes
*High organics. Not removing decaying/rotting plant matter or overfeeding are the most common organic causes.
*Poor Water Circulation. In a planted tank, it can be difficult maintaining water circulation and not having any "dead zones" where the water current is unable to move nutrients.
*Old Light Tubes. Lighting output changes as the tubes age. Standard fluorescent tubes should be replaced every 6-9 months; T5HO tubes every 18-24 months.
*Inadequate fertilization. Maintain proper balance with fertilization: 10-20 PPM NO3; 0.5-2.0 PPM PO4; 10-30 PPM Ca; 2-5 PPM Mg; 0.1-0.2 PPM Fe; KH 4+ degrees/drops; GH 4+ degrees/drops

How to Remove
*Blackout 3-5 days. This bacteria quickly dies from lack of light
*Excel or Hydrogen Peroxide Treatment. Turn off all filters and air pumps to stop the water current. Use a syringe to spot treat the bacteria. Wait 30 minutes and carefully remove the bacteria.
*Take necessary steps to balance nutrients. Dose enough KNO3 to maintain 5 PPM or more.
*Fast Growing Plants. The faster a plant grows the faster it takes in nutrients. Fast growing plants will out compete the bacteria for nutrients.
*Erythromycin/Myracin - Dose at half strength. Use antibiotics as a last resort! Can have a negative impact on the cycle
This is just a start. As time allows I will add other forms of algae.

Courtesy of Dena's algae thread:

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I should add that I have a lot of amazonian frogbit and other floating plants in both tanks,
lots of crypts and other fast growing plants,
they have new lights the 200 is running 2x39w 9hr period,
the 300 is running 4x39w t5ho 2 tubes running for 9 hours 2 tubes running for 8 hours (trying to do a soft on soft off kind of lighting the first two come on 30 mins before the second two and go off 30 mins after the other two)
I dose daily with liquid carbon, and weekly with potassium and profito
water changes are 1/3 weekly,
the area in the 200 where the cyano is taking hold is directly in the flow of a power head and is probably the fastest flowing part of the entire tank (hence why it is confusing me) I have cleared it up before by overdosing the tank with nitro (easylife's liquid nitrate fert) that's what made me think it is an imbalance in my water hence the test for phosphate today, I don't really want to go down the route of overdosing my tank on nitrate every time I get cyano I would rather find the cause than be dealing with the effect if that makes sense but tracing the cause is killing me, by rights my set ups shouldn't be having these issues that's why I thought going for an ro unit will remove what ever it is that's causing this imbalance

ps not sure if this makes sense to any one but this is what I am getting from my water supply according to the local water board

avg hardness hardness classification degrees clark degrees german
130 52 slightly hard 9.1 7.28

test limit no. %compliance min value max value avg value
ammonium (mg/l nh4) 0.50 37 100% 0.009 0.015 0.009
chloride (mg/l) 250 8 100% 11.400 20.600 17.163
chlorine free (mg/l) - 232 100% 0.020 2.300 0.299
chlorine total (mg/l) - 232 100% 0.080 2.900 0.380
nitrate (mg/l no3) 50.0 8 100% 2.938 18.089 9.433
nitrite (mg/l no2) 0.50 8 100% 0.003 0.003 0.003
ph 6.50 38 100% 7.200 8.370 8.047
phosphorus (ug/l) 2200 8 100% 621.000 940.000 710.750
sulphate (mg/l) 250 8 100% 23.600 43.000 29.838

 

Cyano can be a difficult form to eradicate! This form of "algae" is actually a bacteria that is feeding on something that is in your tank.

Make sure there is no debris on the gravel bed. Remove dieing leaves and other decaying plant matter. Deep gravel vac in the open areas and under rocks, driftwood and other hardscape items.

Put the tank into a blackout to gain control over it. And reduce the photo period to 6 hour max until it stops growing. If it is coming off in sheets, be very careful as the tiniest spec that breaks free with start a new colony in a different location of your tank.

I am not familiar with profito. Is it a balanced fert? If not try to find something that includes both macros and micros, or switch to dry ferts.

Nothing I have seen indicates that phosphate or silica is a cause of cyano. Even with the high levels of PO4 in my tap, and using silica sand I do not have issues with cyano.

Good luck! It's going to take some time to remove it.

 

Yes profito is their base fert with all the trace elements required, the rest of the range is designed as an add on from that base