Algae & the fertilizer regime

[plantedpot]

First of all, I would like to credit the author of the website for what I am about to discuss - the Redfield Ratio. Those of us who wish to know more about this RR, please refer to the weblink

http://buddendo.home.xs4all.nl/aquarium/redfield.htm

I chanced upon this page in googling for ways to combat green dust algae. The RR is a formula for recommending the ratio nitratehosphate in our waters in order to hit that elusive spot of no algae. Inside the page, one would find a useful table to the desired type of ratio, as well as a calculator on how much to add to reach the desired ratio.

Well, since my tank is currently infested by GDA due to the extra powerful light for my e.Quin, i tot why not try this out. Prior to my experiment, I had to scrap my glass everyday, so why not?

I started 3 days ago. When I measured my phosphate and nitrates before i started, (Phosphate using a API 2-bottle solution test kit, Nitrate, Nitrites using API Master Test Kit)


Day 0 (Experiment start day)
Phosphate : 0 mg/L (this is one of the reason why I wrote this post as well, to be elaborated later)
Nitrite : 0 mg/L
Nitrate : 5 mg/L

So in order to achieve a 1:16 ratio, I need to raise the phosphate level to 0.5mg/L. Using SeaChem Phosphate, i would need to dose about 20ml. This is actually very scary for me. I've read about how Phosphate not being a very forgiving fertilizer to fishes/aquatic fauna. While I had none of the expensive fishes to begin with (all my fauna are complements to my flora), I have grown rather attached to my SAEs, plecos, otos, BNs and ballon tetras. My fert regime is like 3 ml everyday for phosphate, this sudden need to dose nearly 7 times the usual dose unsettled me somewhat. Anyway, I got my phosphate filter media ready in case of any emergency.

For the first few hours, there wasn't any special behaviour I can observe from the fishes. Subsequently, I noticed that they did slow down by a bit, the SAEs were less darty (became more dormant and stayed still more), the balloon tetras stay relatively closer in their school, otos were glued to the glass, the plecos were hiding and not visible. This went on till the next day, and the first thing I noticed on the second day was the glass became less stained with green...

I measured the Phosphate/ Nitrate/ Nitrite again. This is about slightly more than 24 hours since the last measurement

Day 1
Phosphate : 0 mg/L
Nitrite : 0 mg/L
Nitrate : 5 mg/L

This indeed puzzled me. Why I am glad that GDA did decrease significantly, I was curious as to why Phosphate could bottom out just 24 hours after raising it to 0.5mg/L? Can someone help me understand?

Since i didn't kill any fish, I repeated the dosing for phosphate as well as the normal fert regime for my other macros and micros. There was something I did different though, I didn't scrap my tank. I wanted to see if my plecos and otos are sufficient to clean them out. As a comparison, I would say the GDA which developed overnight was at least 50% lesser than before this increased phosphate dosing.

Day 2
Phosphate : 0 mg/L
Nitrite : 0 mg/L
Nitrate : 0 mg/L

Again the phosphate bottomed out. This time round, the nitrates bottom out as well. However, I did notice a lot of new growth on quite a few plants - Echindorus had new shoots coming out, Eusteralis was full bloom almost like a chrysanthemum (towards the new spot light),


eleocharis grew denser and taller. So in this case, I attributed the bottoming out to the growth. The more important point was the GDA, there isn't any new GDA which I could spot (or at least remember). But there is definitely less GDA on the glass than Day 1 - which could mean either GDA were consumed by fishes, or they fell off the glass.

Do GDA fall off the glass themselves?

Day 3 (Today)

Day 2
Phosphate : 0 mg/L
Nitrite : 0 mg/L
Nitrate : 0 mg/L

I am feeling good and worried. Is my Phosphate tester spoilt? Why is it testing 0 all the time? While GDA is almost gone (except for on my hardscape), is it normal to be dosing so much (20ml Seachem Phosphate) everyday? If so, I may need to consider other more sustainable way of dosing Phosphate. 500ml SeaChem Phosphate cheapest i got is 13/ bottle. If I am using 20ml everyday, i will use one bottle every 25 days. While $13/ month may seem affordable to most, I would want to see if there are better but cheaper way of doing things.

Many things puzzle me about this experiment

1. Do plants uptake a lot of phosphate? If so, why is it that the nitrate/ phosphate ratio is such that nitrate dosing is higher?
2. Do phosphate harm fauna? Is the slowing down of the fauna after the initial increase dose attributed to the same?
3. Do fauna also build up tolerance to Phosphate? The faunas have gone back to their active selves after Day 1, even after the same increased dosing.
4. Do GDA fall off the tank walls themselves?

Please share with me your thoughts and expertise for this experiment.

Thanks

[Apistoinka]

Following.. very interesting..

[Zep]

Here goes my experience.

Started off with some GDA but I ignored it since they weren't too bad and the tank glass cleaning was about once a week.

Then my heteranthera zosterifolia started to show signs of deterioration and blackened tips. I read up on it and thought it could be a phosphorus deficiency. Went to get the Api Phosphate test kit and true enough PO4 tested 0.

Went out to get seachem phosphorus and dosed according to the bottle's instructions. GDA started to lessen. Heteranthera improved. But P04 testing continued to show 0.

Thought I didn't dose enough and wanted to get PO4 to about 1-2 ppm. So I increased the PO4 dosage to 3ml daily (mine is a 2ft tank). After dosing for a few days PO4 still tested either 0 or 0.25ppm.

I thought my Api testing was not working so I tested it by dropping seachem phosphorus directly into the test tube. Phosphorus testing shot up.

Now that I have finished using the bottle of seachem phosphorus I switched to aquatic lawn phosphorus (home made fert by one of the bros in the forum, much more affordable than seachem phosphorus in the long run) and I dosed it so that PO4 will reach 1-2ppm according to the instructions in the bottle. API PO4 test still registered 0-0.25.

I don't know what's wrong with the testing. But my GDA disappeared and my plants are doing well. PO4 seems to be bottoming out everytime.

So my conclusion is that phosphorus dosing really helps to get rid of GDA and it helps the plants. But the testing part is still a mystery.

[plantedpot]

Thanks Zep. Can share the homemade phosphorus fert price and contact?

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[Xiaozhuang]

just use KH2PO4 dry powder from hydroponics shop, it's very cheap once you go the dry powder route. The reason why tests keep testing 0 is that phosphates are reactive and bind readily with other substances in the tank. Depending on what it binds to, it may precipitate out into the substrate etc. Rooted plants can still use it in that form. The short answer to the RR is that ratios themselves don't automatically give an algae free tank - people have been going in that direction for years. You can have algae free tanks regardless of the ratios; it depends more on light control, plant mass, plant health(which are dependent on a host of other variables along side ferts - CO2, flow, etc) .

[Zep]

Hi plantedpot, I bought the ferts from bro Harryxing. You can search the forum for Aquatic Lawn and his thread should pop up. Contact him for pricing and details. I was lazy to try the dry fert route so I went to get his ferts. So far I am using aquatic lawn potassium and phosphorus.

Hi Xiaozhuang, thanks for shedding light on the testing. Now I know why my PO4 always shows up 0-0.25. I read that PO4 will precipitate with Fe. I have been trying to dose those 2 ferts at least 15min apart. Does that help to prevent the precipitation? What other elements does PO4 bind with?

[Xiaozhuang]

Phosphates bind with many things aluminum, calcium, and soils/clays. But the reactions are concentration and pH dependent. (similar for iron chelates; depending on your tank's pH different form of iron chelates break down at different rates). Regardless, if you dose phosphates regularly, your plants will get to the phosphates even if they are binded to substrate.

I dose iron and phosphates on the same day, barely minutes apart... Unless you see a white cloud of white precipitate, I don't really think it matters

[Zep]

Thanks Xiaozhuang. That's great info. Seems then that I do not really have to test for PO4 already. Anyone looking for PO4 test kit can pm me.

[Apistoinka]

So reali by dosing phophurus really slow down gda growth..

[plantedpot]

just use KH2PO4 dry powder from hydroponics shop, it's very cheap once you go the dry powder route. The reason why tests keep testing 0 is that phosphates are reactive and bind readily with other substances in the tank. Depending on what it binds to, it may precipitate out into the substrate etc. Rooted plants can still use it in that form. The short answer to the RR is that ratios themselves don't automatically give an algae free tank - people have been going in that direction for years. You can have algae free tanks regardless of the ratios; it depends more on light control, plant mass, plant health(which are dependent on a host of other variables along side ferts - CO2, flow, etc) .

Thanks for the info. For newbies like me, its much easier when there is some formula to follow. Still in the learning stage so can't really based on my own experience on how much to dose for the macro/micros. With the assortment of plants I have, some reacting entirely different with the same fert regime, I guess a ratio helps nudge me in a certain direction so that i won't kill one species of desired plant in the process of trying to make another thrive.

Eventually I do hope to be able to grow some Rotala Sunset/ Florida if I can get my hands on them.

[plantedpot]

Day 4

Phosphate : 0 mg/L
Nitrite : 0 mg/L
Nitrate : 5 mg/L

There is something else different I observe today.

1. The larger surfaces which are exposed to the ebb and flow of the HOB filters, as well as those exposed to the circulation pump are free of GDA.
2. The inner surfaces of the planted pots are coated with GDA.

Overall look tank is cleaner than yesterday, despite me not scrapping it for 3 days already. I might take out the planted pots and clean them up a bit and see if more GDA will appear tomorrow.

So GDA is dependant on flow as well? Poor flow = more GDA?

[DreamerX5521]

Alternatively, you may try seachem neutral regulator dry powder, if you have any on hand now. It is phosphate based solution to buffer ph level.
My low tech tank also constantly btw 0-0.25ppm level for phosphate. There was one time i tried dose the dry powder straight into the tank, the next day i measure it and i got a 5ppm of phosphate.
However, i'm not sure if the phosphate is with the same form as the liquid form of seachem phosphate. But you may try it if you happen to have it on hand.

[plantedpot]

The neutral regulator is $33 per bot and too big a bot to buy and try. I bought the discus buffer which goes at 10 and about 250g (IIRC). Using 2 teaspoons to 500ml of RO water, i mixed up a phosphate solution. Have been dosing the phosphate solution for my tank for several days now. The GDA is gone, but there are too many things which I did as well (using BorneoWild Phyton; adding a few strands of ceratophyllum demersum; adding a bunch of Hygrophillia difformis)

[Xiaozhuang]

Buying KH2PO4 is only about $20 dollars for 500grams...

[plantedpot]

I dunno where to buy. Saw a few florist shop selling dry fert but all is npk mixtures and the n is always got urea or ammonium...

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[DreamerX5521]

You may look for hydroponic for the kh2po4 dry fert
http://www.singaporehydroponics.com/...d=66&Itemid=72

[Xiaozhuang]

You may look for hydroponic for the kh2po4 dry fert
http://www.singaporehydroponics.com/...d=66&Itemid=72

http://www.ecocityhydroponics.com/hy...e-farming.html

will deliver for some cost, or self collect

[AQMS]

Buy dry fert will last longer. Go for it,it is a huge saving.

[plantedpot]

Thank you dreamer, xiaozhuang and AQMS for the links and advice

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[AQMS]

I usually bought mine from here the whole shebang http://www.aquariumfertilizer.com/in...tion1=products
bought a lot and last for more than a year.