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Discussion Starter · #1 ·
Originally posted by tzalmaves:

Hello,

I've attached three pictures of my plants. I'm trying to figure out what is causing the brown algae and the "dry" leaves on the bacopa that happens after the leaves have been around for a while. Even new leaves grow with a brown "viened" pattern

I have a 37 "tall" (All-Glass #10037 37 Gallon 30"x12"x22") aquarium with an Eclipse 3 hood with a DIY 3rd light (as of January '04) for a total of 2 x 18w + 55w = 91 watts of light. Before that the stock 36 watts of light. Lights are on for 14 hours. About 2 inches of substrate - 50% gravel, 50% flourite. DIY CO2 using 2 2-liter bottles and the sugar-water-and-yeast method. Wood airstone for fine bubbles. Fertilize (as of January '04) with 5ml PMDD daily. 2 20% water changes a week. I have about 20-25" of fish, and dozens of little snails (though my newly aquired dwarf puffers are rapidly reducing that number). Ph is 7.4ish, GH: 13, KH: 8, Iron: 0.1mg/l, Nitrate: 10ppm. I accumulate a light dusting of green algae on the front glass during every 5 days.

I hope you can help me - I'm getting close to giving up on the whole thing. :(



 

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Discussion Starter · #2 ·
Posted by spituch:

Dear tzalmaves,

I am not an expert but I give a try.

I had Bacopa monnieri where the bottom leaves would fall off. I was not dosing enough.

PPMD is 1390 ppm Fe (1.39 mg/ml). Per your dosing regimen your saturation level would be 88 ml of PPMD (5mlx7days/.4), or 122 mg Fe. Thats .92 ppm Fe in 35 gallons, which is a good dose. (Somebody check me on this).

So I would try to add 1 ppm PO4 using the Enema method or KH2PO4.

Everything else looks good to me. Hopefully someone else will find something. Usually brown diatom algae to due to lack of light but your light seems Ok.

Steve Pituch
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Steve,

You want me to add phosphates? I thought the fish produce that.

Can you explain (or point me to an explanation) of your saturation formula? Why do you divide by 0.4?

-TM
 

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Ok, here goes,

If you were to add 1 ppm per week to a tank and not do any water changes and the plants didn't take in any of the nutrient, the amount of concentration would increase by +1 ppm per week: 2 ppm 2nd week, 3 ppm 3rd week, etc.

If you do a 50 % water change every week. you would get 1.5 ppm the 2nd week, 1.75 ppm the 3rd week, 1.875 ppm the 4th week, 1.94 ppm the 5th week, 1.97 ppm the 6th week. All I am doing is cutting the total in half because of the 50% water change and adding +1 ppm. This series converges to 2.0 ppm. So for a 50% water change per week, adding 1 ppm per week, you can never go over 2 ppm per week. The purpose of the water change is to keep your nutrients from becoming too concentrated.

So for a 50% water change once per week divide the weekly ppm dose by .5 (50%) to get your limiting concentration.

You do two 20% water changes per week. I am lazy so I rounded this to 40% (.4).

Actually to be more accurrate you do one 20% water change every 3.5 days. So the math is 5ml x 3.5 days/20% =88 ml which is the same. Multiply by 1.39 mg/ml to get 122 mg of Fe.

122 mg (Fe/1liter)= 122 ppm Fe. We are diluting this with 35 gallons=(3.77 x 35) = 132 liters 122/132= .92 ppm Fe in your tank maximum concentration.

You are actually adding .92 x .4 = .37 ppm per week.

The joy of the method used by Tom Barr (plantbrain) is that you can dose relatively high concentrations, but the 50% water change limits your concentration of the nutrient. If you want to stay say between 10 and 20 ppm K, simply dose 10 ppm K per week and do 50% weekly water changes. Your K will never go above 20 ppm.

Per Walstad's book, low light tanks with a soil substrate all the macronutrients are provided by overfeeding with plant food. The plant food processed by the fish provide P,N,K and C. Its not the fish that supply these nutrients its the fish food. All of the micronutrients are provided by the soil. (a lifetime supply of Fe and other traces).

You have a higher light tank. You must provide micro and macro nutrients to keep up with the higher demands of plants that are photosynthesizing at a higher rate. Fishfood is not enough. Thats why you use PMDD and KNO3. Phosphate is the same thing, you need to supply it. If you have been reading the Conlon & Sears paper, a lot has been learned since that important paper was published. Don't try to totally limit a certain nutrient to prevent the algae. If you truly accomplish this, you'll kill the plants (or the leaves will fall off of your Bacopa). :D It does take a leap of faith to first add that P, but what I have found is that if you have enough of all the nutrients the algae won't get worse (it may not get better, but we are all working on that).

Your plants are probably sucking up all the available phosphate from the fishfood.

I would wait for someone else to chime in on this before doing anything. The great thing about the forum is that you can get a second (and third) opinion. Somebody else might feel that 2.5 Watts/gal is not enough light for B. monnieri.

Regards,

Steve Pituch
 
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