Ugly Green Spot Algae

[Aquabum]

What causes green spot algae? I have it in nearly all of my plant leaves. My pennywort looks awful with this stuff. Some say it's caused by high light, and others say it's caused by too much Po4.

The Po4 out of the tap is pretty high (about 4). My plants do use the Po4 and in about a week's time, it's nearly 0. Is this still a problem? Should I use Phos-Zorb?

My tank is a 29 gal. at 2.5 watts, this is considered medium light, right? Nitrite, and Ammonia tests are 0 except for Nitrate which is at 10.

Any help will be appreciated.

[djlen]

Keep a close watch on your P level. The rule of thumb for N/P relationship is 10/1.
Figure out a way to get these two into balance consistently, and add some floaters 'til you find that balance. Are you dosing N and if so, with what? KNO3?
You don't mention traces. Are you supplying any for your plants?

Len

[Aquabum]

Hello Len,

Yes, I'm dosing KNO3 whenever it's needed, I always aim for 10. Is this too high? I'm also dosing Flourish 2x a week. The plants are doing well, I'm always pruning them.

I purchased Phos-Zorb which I just placed in my filter. Is this okay? I can't do anything else about the tap water.

Len, do you think it's the Po4 or the lights causing the green spots?

Thanks for your help.

Lissette

[djlen]

Lissette - take a sample of your tap water, let it sit for 4 - 6 hrs. and test it again for P content. Also test for N.
A result of 4 seems awfully high for Brooklyn. What kind of kit are you using?
What is your plant load like? Types and Mass?

Len

[Aquabum]

Len,

I have taken some tap water to sit for 4 to 6 hours as you adviced. I will test for P and N and post the results for you.

I tested the tap water again today and it comes out a dark blue. According to the chart it's darker than 2.5 to 3. Sometimes I can't really tell since the colors are somewhat close together in shades. I also tested the tank this morning and the according to the kit, P is near to 0. (just wanted to let you know this)

I'm using the Nutrafin Hagen Kit for Po4 and I'm using the Aquar. Pharm. kit for N03. Plant mass is moderate (stem plants). I'm looking to buy more plants (high light) and retrofit a 55 CF to support them, but I'm worried about the green spots.

Thanks for your help.

Lissette

[Aquabum]

Len,

I tested the water at 9:00 p.m. for P and for N. According to the test, Phosphates was 2.5 to 3 (the blue color in the tube is a bit darker than on the chart). Nitrates read 0.

Thanks.

Lissette :)

[Lazonby]

GSA is my indicator of too little PO4, or an imbalance of the N:P ratio, but usually a lack of PO4. Either add PO4, or do a water change since your tap water has plenty of phosphates and dose only nitrates.

If you happen to have high phosphates and low nitrates, say a 3:1 ratio, you will get lots of algae, and high light can help produce some GSA. Be sure to keep your nitrates much higher than your phosphates. I believe the ratio is actually 16:1. Either way, 10:1 is a minimum.

[djlen]

I agree for the most part with Lazonby.
I wouldn't worry about your tap water at the levels you report. Your plants are using P when you balance it with N.
To help with the algae you're having a problem with, you need to balance these two elements better, and increase plant mass. I would suggest, in the process of increasing mass, you pick up some Riccia or Salvinia or Water Sprite to help use nutrients and shade the tank a bit.
I dose N and P heavily. My N value regularly stay's in the 20 - 30 area, with no problems for the fish, and P in the 1.5 area. If you are doing regular water changes, you should have good results with pushing your N to balance your tap's P content.
Don't be afraid to push the N, and shade the tank until the rest of the mass increases.
If you are not dosing traces, I suggest you start. It's all part of the balance.


Len

[Aquabum]

Thanks guys.

I'm heading to the lfs to buy more plants and I'll dose some more N03 and traces to try and balance everything out.

You guys are great!

Lissette ;)

[plantbrain]

I'd check your CO2 good.
If it checks out well, especially if you measure it both at the start,middle and end of the light cycle, then you can move to the next item.

I'd add 3x a week: KNO3, 1/4 teaspoon.
I'd add 1/16" teaspoon of KH2PO4 2 a week, add 3 days after water change.
If the PO4 is zero at the end of the week, that's bad and I suspect poor test kit, not 2.5-4ppm of PO4. So it's likely less than than the readings you have.

Traces: add 5-7mls 3x a week.

Scrape off the GS with a credit card, preferably the spouse's. Better use for it anyhow.

Clean well, then do the above changes.
Low CO2 and also low PO4 will cause GS.

Anyone that believes huigh PO4 causes any algae, well, I am still wondering where my GS and many other species are and why I have to prune so much.
That was 15 years ago, I am still waiting.
If anyone can explain why I do not have it when they cvlaim high PO4 causes it, I'd love to entertain their notioins as to why my tanks and many other folk's don't have algae.

Regards,
Tom Barr

www.BarrReport.com

[Aquabum]

Tom,

I was thinking the same thing about my Po4 kit being faulty. My lfs assured me that the Po4 kit is good. I read somewhere that the Hagen plastic bottle reagent #3 wasn't good, but I have the glass bottle, which is supposed to work. I'll see if I can buy a new kit from a different brand and check the results.

The kit detects Po4 in the tank the day I do water changes (which is once a week), but two to three days later, it detects nothing (I figured the plants gobbled it up). Your post confirms this. So now I see that I'll have to add more Po4 to balance this out with the N that's still in the tank. It seems that my plants prefer Phosphates over Nitrates.

My DIY Co2 is running about 28 ppm. I change the mix (frequently) when I see less bubbles in the ladder.

I've given my plants the traces, Po4 and Kno3 as you've suggested. I've also bought more plants.

Thanks Tom, your help is greatly appreciated. ;)