Black algae

[ash42]

Hi folks

I am hoping someone out there can help me with an algae problem - black brush like algae and lots of it! I've been keeping fish for several years and 12 months ago when I used treated tap water I rarely had algae problems but since swapping to RO water this black algae has become a real nuisance in both my tanks.

Tank 1

Volume: 300 litres
Lighting: 160 watts from 4 florescent tubes
Filter: Eheim 2128
CO2: JBL CO2 system with PH controller
Substrate: Dennerle Duponit mix covered with fine quartz gravel Rena heater cable
UV fitted following a scare with my discus

Tank 2

Volume: 120 litres
Lighting: single 30 watt florescent tube
Filter: Eheim ecco 2235
CO2: DIY yeast system
Substrate: fine quartz gravel with root tabs

Water parameters for both tanks:

PH6.5
GH7
KH3
Ammonia 0
Nitrite 0
Nitrate 20mg/l
Phosphate 0
Iron0.5mg/l

I have checked the RO unit and the water produced is fine, moving back to tap water is not an option as I keep discus now. Any thoughts on how I can get rid of the algae? All suggestions gratefully received.

Ash

[juggler]

It should be due to excess NO3. In the sense that you do not have enough PO4 to balance it. Do you dose this compound?

What liquid fertiliser do you use for dosing?
Do you also dose for Potassium?

Whe you were using tap water, did you already have those discus? Discus produce a lot of NO3 and that could be the reason fo the higer NO3.

You can read more about dosing from the threads in the FAQ section.

[PeterGwee]

CO2, CO2 and more CO2. You would not get this type of algae if your CO2 is indeed high and good unless you overfeed or have too much fishes in the tank. What you can do is to check the probe of the pH controller and recalibrate it if necessary. Note that DIY CO2 is notorious for inconsistency in CO2 supply and tends to wear off towards the end of the week so you need to keep up with the supply by constantly changing the brew. Having zero phosphate is no good...it is a plant nutrient and limiting it limits the uptake of NO3 if the rest of the nutrients including CO2 is in good range. Trim off the BBA as much as you can...do a large 50-70% water change and correct the CO2. Keep a close eye on the CO2 level and make sure it is in the 20-30ppm range during the entire photoperiod. The algae should stop growing when the CO2 is good and then it is when you have it beaten. You need to work on the plant nutrients after you have corrected the CO2.

Regards
Peter Gwee

[PeterGwee]

[quote:3588233be6="Juggler"]It should be due to excess NO3. In the sense that you do not have enough PO4 to balance it.[/quote:3588233be6]

KF, it is not due to the excess NO3 unless you mean ammonia from critters in the tank that is. You can have BBA in zero NO3 or high NO3 environment as long as you slack on the CO2. Folks need to be critical about this measurements, consistency of the kits and potential errors need to be included. Add more when you are in doubt but do monitor the critters behaviour just to be sure.

Regards
Peter Gwee

[bclee]

Ash, after studying what you posted, here is my observations:

The algae problem only come about after:

1. You switch from tap to RO water
2. Addition of discus (you post implied that you switched to RO after acquiring the discus)

A few things has happened.

1. RO has removed the nutrients present in the tap water.
By removing nutrients from the water using RO, your plants are starved of some nutrients like PO4. This will cause the algae to overtake the plants. Algae has lesser nutrient demands compared to plants.

Solution:
- You need to supplement your macro nutrients with stuff like KNO3 and KH2PO4.


2. Addition of discus increase the bioload and NH3 level (although not captured in your water tests, it is there)
NH3 most of the time do not turn up on the test kits. But you know they are there especially after you added the discus. This NH3 are used up by plants and algae. Algae prefer NH3. With increased NH3, algae thrive. Your high NO3 reading are probably from the NH3 that has been converted to NO3.

Solution:
- Dose NO3 and K. NO3 gives the plants an edge over algae. K will help the plants with N uptake.
- Plant heavily.
- Ensure your filter are working effectively, ensure that they are not clogged.

Giving sufficient CO2 is also the main key as Peter has mentioned above.

BC

[Plantbrain]

Add more CO2, Discus are fine a KH of 5-6, I've bred them at that level.

You can use the RO, that's not an issue really as long as your KH is 3 or higher generally.

You do not have enough CO2. 20-30ppm in a good range, no less.

Then you can move on to adding more traces, KNO3, KH2PO4(or some source)

If you have a reasonable stocking level for the fish and do not overfeed or constantly try and give them food, your NH4 levels can be okay.
But if you have 6 full grown fish in a 200 liters tank, and feed 2-4 x a day.......then you are never going to have an easy time with plants.

A good filter can help this, but at some point even a super filter and all the plants and CO2 will not be able to stop algae.

Try adding more CO2, then see about KNO3, then PO4 and finally traces.
That should work provided your stocking levels and feeding are within reason for the tank size.

Regards,
Tom Barr