Background covered with brown (slightly red) algae....please identify

Tank has been established for 2+years. 70w t5 HO. 150 litres. 40% water changes weekly. EI dosing. Co2 @ 30ppm approx, controlled via ph meter.

Please identify the algae....it covers all of my 3d background and on some plant leaves. I suffer from very very little green algae but the brown stuff won't go away.

That is a type of black brush/beard algae. It is technically a "red" algae, but it can also appear as black, very dark brown (some confuse it initially with diatoms), or very dark green/grey. It has more than one form, which may be different "species" I'm not sure, but it can appear as tufts or a sort of carpeting as in your photos. The plant close-up shows it very well as black carpeting.

The cause is an imbalance between light/nutrients. I have had the carpeting form occur from overdosing fertilizers, from too long a duration in lighting, and from too weak light (tubes needing replacement). In all of these the balance was simply out.

I am not going to recommend a treatment because you are using a high-tech method (I follow natural or low-tech). But somewhere your balance is out.

Byron.

Improve water circulation (what filtration do you have) and reduce photo period slightly. Dosing with liquid carbon will help too as it's an algacide and will also benefit your plants.

Have you tested for ammonia?

EI dosing. Co2 @ 30ppm approx, controlled via ph meter.

Click to expand...

First thing I would do is verify your CO2 level is correct and verify your PH meter is calibrated. PH meter do drift over time so periodic calibration is required. Then I would check your fertilizer against this list of nutrients plants need:
https://en.wikipedia.org/wiki/Plant_nutrition

Many fertilizers are often short one or more micro or trace nutrients. The EI method assumes your tap water supplies the Calcium plants need and many fertilizer manufactures don't put it in the fertilizer. However f you have very soft water you will not have enough calcium in the water.

Have you seen your plants pearl (oxygen bubbles on the leaves). With CO2 injection and fertilizer your plants should pearl. IF they are not your CO2 is wrong or you are low on one or more nutrients. Also the estimative index works best if you apply fertilizers once per day.

Bryon/StandbySetting/StevenF,
Thanks for your replies, I will try to take all points on board and take a multi-prong approach to fix the problem.
Now that I know it is a type of "black brush/beard algae" I can read into it for specific information.

Lighting
I changed my tubes a few months back so they do not need replacing. They are currently on for 8 hours per day. I will reduce to 7.

Fertilliser
I am dosing per aquariumplantfood's recommendation.

http://www.aquariumplantfood.co.uk/fertilisers/dry-chemicals/starter-kits/ei-starter-kit.html

It contains everything from the wikipedia link except calcium and sulphur. I can't find anywhere that doses sulphur?!

I have checked with my local authority and I have soft tap water (see below for recent results)

Clark English Degrees - 1.7
mg/l CaCo3 - 24.0
mg/l Ca - 9.7
Dosing calcium is something I have not considered before, some research is required
Should I replace some of the potassium nitrate with calcium nitrate?

CO2 / Flow
I recently ignored the aquarium for a few weeks after getting annoyed with the algae problem. During this time my CO2 finished and the green tufts appeared. However the brown carpeting has been a continuous feature while the co2 was running.
I am comfortable with the co2 level because my drop checker is lime green before lights on and Ph is constant until lights off. The CO2 system is on a timer which turns on one hour before lights on and turns off with lights off....could the Ph swing at night be influencing the algae?
For flow I have a Fluval 205 external filter (680 l/hr by spec) and a Fluval sea CP1 powerhead (1000 l/hr by spec). The power head runs only during lights on. I think this should be sufficient? In an attempt to improve the flow, I have moved the power head closer to the rear of the aquarium where I experience the worst of the brown algae.

If I fix imbalance problem, how long will it take for the algae to die? I can clean it from everywhere except the 3d background which I don't want to damage.

Once again I will generally leave this for the high-tech experts, but a couple things do stand out.

Water flow/current. I am not at all a believer that this impacts algae. I have this algae most noticeably on the filter return and spraybar, where the flow is strongest, even if no where else in the tanks. So if anything, more water flow would seem to encourage it. But you are unlikely to have the water current as strong throughout the tank as it is on the filter intake/return anyway. So I would discount water flow.

Calcium is an essential nutrient for leaf cell structure, so you should be adding it since it is likely lacking in your soft source water. Sulphur is included in the basic preparations I use and is sufficient, but again I have low-tech systems. Magnesium sulfate (Epsom Salt) is magnesium and sulphur, so you could dose it this way. But be careful, as this can raise the GH (the magnesium does this). I would prefer adding it in to the mix.

One last comment...I am not a believer in the EI method as it is adding way more nutrients than needed, and even with a weekly water change, this can upset the balance. Just my thinking.

Your light is very intense (T5 HO over this sized tank), so a reduction in duration may help a lot.

Byron.

according to the Wiki article the needed elements are:
N/P/K/Ca/Mg/S/B/Cl/Mn/Fe/Zn/Co/Mo/ni

You have:
N/P/K/*/Mg/S/B/*/Mn/Fe/Zn/Co/Mo/ni

Magnesium sulfate is in the product you referenced and that takes care of the sulfur. You are actually short 2 elements Chlorine and Calcium. Calcium chloride will solve that but there are some additional items you need to be aware of:

1. calcium chloride will react with your magnesium sulfate resulting in magnesium chloride (water soluble) and Calcium sulfate a solid that is barely soluble. Keep the calcium chloride separate from the other fertilizers don't mix them together in a bottle before use. Hydroponics web sites recommend 4 parts calcium to 1 part magnesium. that will result in Excess calcium chloride. after adding the other fertilizers wait to insure the fertilizer is thoroughly mixed with the aquarium water and then add a calcium chloride solution slowly. That will solve both problems. I only recently learned of this sulfate reaction that can result in sulfate, and calcium deficiencies in aquariums
2. In theory adding calcium chloride to the tank will result in excess chlorine in the water. I have crushed see shells in my filter. That will react with any excess free chlorine release a little bit more calcium chloride which is safe.
3. You are dosing KNO3. As the nitrogen gets used up excess potassium builds up and that generally result in a PH rise as the nitrogen gets consumed. You might have enough excess potassium to react with chlorine to form Potassium chloride which is also a fertilizer and will not affect ph. so you may not need crushed sea shells I use to consume the excess chlorine.
4. Calcium nitrite is another possibility (one that i am considering myself). However like all other calcium salts with will react with magnesium sulfate. So like calcium chloride it must be added separately. To add the chlorine needed you can add table salt sodium chloride or potassium chloride. Note potassium sulfate (a common potassium fertilizer) will also react with calcium.

5. Clark English Degrees - 1.7
   mg/l CaCo3 - 24.0
   mg/l Ca - 9.7

   Click to expand...

   Gh is a reading of magnesium and calcium salts together. calcium carbonate may or may not be actually present. 1.7 degrees or 24.0ppm is the equivalent calcium carbonate value. The 9.7 mg/l Ca is the real amount of calcium in the water and it may not be enough to after reacting with the magnesium sulfate you are adding.

I have been suffering a 2nd bout of hair algae for some time. Since I discovered the calcium sulfate issue. I have since gone to a 4 to 1 ration of Ca/Mg and have kept them separate. It has only been a couple of weeks but the green spot algae on my class (which never bothered me) has declined but the hair has not yet changed. I am going to try reducing my lighting this week. I have no idea how long it will take to clear the algae. I have to assume that once you clear one issue you will find a second one.

Note calcium chloride is readily available at some hardware stores but it is typically sold by the pound which is a lot for the small aquarium i have. Given your suppler has calcium nitrate that might be a better choice for your. I got my calcium chloride from: http://www.loudwolf.com/store/index.php?main_page=index&cPath=8