Need Algae EXPERT help

tanker

tanker

Josh Holloway--Be mine!!!
Sep 1, 2003
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Jessica
I have a 100 gal VERY heavily planted tank. For lighting there is 384 watts of PC light. I have a 20lb CO2 tank set for about 15 bubbles every 10 seconds. The CO2 comes on 1/2 hour after lights coem on and is shut off 1/2 hour before lights go off. Tank has been running for over 5 years without algae.

Problem-- About 2 months ago I ran out of CO2. Local welding shop ran out too. Took 2 weeks (yes 14days) to get CO2. Well I started getting algae, the small bright-green hair balls EVERYWHERE. I thought that after getting new CO2 the problem would fix itself--WRONG!!
My tank is still full of algae. My beautiful dwarf sag is covered with it--Looks like a green Muffet (Green Elmo) is laying in my tank. It has been 2 months now. I have INCREASED my water changes without success. What now??
I cannot measure any Nitrates nor Phosphates (I really do have lots of plants.
What should I do?? :sad
 
You need to get your nitrates up to 10ppm and your phosphate to 1ppm. What is your CO2 concentration? BPM doesn't tell anybody anything. How long are you leaving your lights on? Anything more than 10-12 hrs and your asking for trouble.
 
Step 1: Increase CO2, have it turn on before the lights so that it's already dissolving into the water. Aim to have a concentration around 30ppm. You've got pressurized, so you should be able to get a pretty rock solid level.

Step 2: Dose NO3 and PO4 in a 10:1 ratio (10ppm NO3 and 1ppm PO4)

You can do this without a test kit if you have the dry ferts. Download Chuck Gadd's nutrient calculator (it will calculate your CO2 concentrations from pH and KH as well). After your water change, add enough KNO3 to bring your tank to 10ppm, add enough KH2PO4 to bring the concentration to 1ppm. You can get the dry ferts from www.gregwatson.com .

Halfway through the week add a half dose to make up for the ferts consumed by the plants.

This is a condensed version to Tom Barr's Estimative Dosing Index (credit where due). I've probably missed something, but I'm pretty sure that's the meat of it.
 
Pruning is a definite. The above steps should stop algal growth, but they won't eliminate existing algae. I have noticed a definite increase in growth by increasing NO3 from 10ppm to 15ppm, but I think that 30ppm might be excessive.

Oh, I just remembered, do a 50% water change every week. The idea with the estimative index is that the dosing prevents nutrients from running out and the water changes prevent any buildup.
 
I agree with happychem and using Toms Est. Index. However, at 3.84watts of PC (and the fact that you cannot measure NO3/PO4), you may need to dose more than 1/2 dose at midweek. Seems that heavy plant load would use up those nutrients a bit faster given the lighting AND assuming the CO2 is >20ppm. Sounds like this is the case if your NO3/PO4 are undetectable.
Good luck!
p.s. by answering this thread I in no way proclaim myself an "algae expert"! ;)
 
Thanks for all the replys:

My lights are on 10 hours per day (7am-12pm then 1pm to 6pm).

JAY: Thanks for correction--I was thinking WOW NO3 at 30ppm?? I need to find some Nitrates!!! :eek:

My CO2 is over 20ppm but wouldn't adding extra nutrients only encourage algae?? This is the first time my tank is getting algae this Century. ;)
 
Not necessarily. You want to encourage plant growth as much as possible. Most algae cannot use NO3 as a nitrogen source, so NO3 is of no use to them. If you have no/little PO4 then the plants cannot grow and take up NH3 properly (which algae can use), so having some PO4 there is a must. Limiting PO4 in a planted tank is foolhardy, since we all acknowledge that algae are better at scavenging limited nutrients than plants, having very low level of PO4 only hurts the plants.

If you have balanced nutrients: N:P in a 10:1 ratio, your plants will grow well and beat out the algae.
 
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