newbie qn on Fertiliser

[eric_kclee]

Don't whack me first...be patient with me...just a question that couldn't find an answer elsewhere.

I read most of the PMDD and Fertiliser Thread...what I ask is only conceptual..not detail calculation...

Here goes the qn:
I have learned the calculation method to dose ...let say NO3 to X ppm to my tank. Fine if it is the first time...just follow the calculation.

The real question is, after my weekly 25% water change (eg. Y litre), how would I dose?

1. Calculate dosage Z for for the newly added water (Y litre)? or

2. Calculate dosage Z for the Y litre and dose Z + e, assumming the plant has consume some amount of fertiliser (e amount)? or

3. Calculate base on the full tank capacity? or

4. Whatever we add we need to maintain the desire ppm. So must check the lacking amount after water change and add on what is needed to meet the Xppm.

I think 4 sound like correct? did I just answer my own question?

All advice are welcome!

[PeterGwee]

There are basically 2 ways to do it. First the estimative index method from Thomas Barr which is based off max plant uptake and large weekly water changes to prevent buildup. The other is through testing with a good kit..(Lamotte is good..sera or tetra does not come close.) I found those cheapo ones to be a bad indicator..(The kit gave me high NO3 reading which I thought so and stop KNO3 dosing. Plants did not grow much at all..seem kinda stunt week after week. I decide to do the estimative method and start dosing KNO3 base on possible max uptake (3-4ppm per day at max growth rate)..plant growth exploded...lots of growth. What do you think? Oh, that is provided the CO2 and rest of the nutrients are met though.

[vinz]

I don't like the estimative method as it requires a lot of water change (50% a week) and I think it's a waste.

The cheap kits give you an estimate value only and a place to start... observe the plants for deficiency symptoms. You can also guess by your fish load and feeding whether you would be on the high or low side of desired levels. The appearance of certain algaes are also indicators of what the problem might be. Some trial and error, and patience waiting for results.

[MikeKoh]

I too face this problem. I do a 50% water change... after that I split a week's dosage (about 60ml of TMG) to daily dosage. I am thinking perhaps since it is divided to daily dosage, the 1st few days may not be sufficient for the plants and may cause slow growth...and algae may result. Should I just put in a whole week's dosage and let the plant absorb as much as they can? My bioload is quite high so I have no problem with Nitrate shortage.

[vinz]

No need daily dosage.. you can dose every 2 or 3 days. The first one can be slightly larger, but its mainly guesswork.

E.g. If your total weekly dose is 60ml, you can try dosing 30-15-15. The bigger dose right after the water change.

[stressed]

I think Item 4 is correct, but that is provided you have the proper test kits.

You need to know current "nutrient" measurement, need to know your new water "nutrient" measurement. Then add e DELTA required to get to the desired "nutrient" level.

For me, some "nutrients" that I dose I do not own test kits, thus I dose based to the minimum required level to be on the safe side. So far, no disaster has struck, no Algae problems too.

[eric_kclee]

hmmm....lots to learn on 'the art of dosing'.

From all responses, it sounds like 4 is correct. Wah....need lots of experiment and lots of 'looking at the plant' work...

My wife already complain that I look at the tank more than looking at her...how could I do more of 'staring at the plant' thingie?...

[theodore]

For K and Fe, I dose using method (3). Read this for the explanation on why it works.

For NO3 and PO4, I usually base my dosage on the rate of nutrient consumption, i.e. method (4).

[PeterGwee]

Using test kits tells you more info but a bad kit with inconsistent results would send you down the wrong path. When deficiencies appeared, it is too late. CO2 and nitrate are the ones that will cause most issue with plants....addition of nitrate through KNO3 would not cause algae even if you are a tad high but the natural means through fish waste is going to as the source is ammonia. When this ammonia exceeds the plants and nitrifying bacteria's uptake rate, it is a feast for the algae and they will bloom nicely. A good kit is a must if you want to go down the line of testing. Even AB's James Hoftiezer is complaining about the cheapo kits which is not giving him an exact clue.

[bttay]

I use method 4 and I do the water test after every change and get complaints from my wife too.[] So far the plants are growing well.

But now that I know my tetra and sera kits are not accurate.

Sorry for the sidetrack: Where can I get the better test kits hah? What about JBL which is slightly more costly?

[PeterGwee]

Bttay, I don't think you would want to spend that much on a good NO3 kit..its just too expensive. If the current kit works well for you, just continue doing it but use plants as a reference rather than trusting the kit entirely. If your NO3 is dropping throughout the week, you should see much growth from plants..if not, drop the kit.

[vinz]

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On 9/10/2003 9:55:24 AM

Using test kits tells you more info but a bad kit with inconsistent results would send you down the wrong path. When deficiencies appeared, it is too late. CO2 and nitrate are the ones that will cause most issue with plants....addition of nitrate through KNO3 would not cause algae even if you are a tad high but the natural means through fish waste is going to as the source is ammonia. When this ammonia exceeds the plants and nitrifying bacteria's uptake rate, it is a feast for the algae and they will bloom nicely. A good kit is a must if you want to go down the line of testing. Even AB's James Hoftiezer is complaining about the cheapo kits which is not giving him an exact clue.
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Which is why you should only use them as estimations. Observe other signs (deficiecny symptoms and algae type) for more clues.

Eric, you don't have to stare at the plants for so long. Not all plants will show the symptoms quickly or at all. Some just slow down. The more reactive ones tend to be stem plants. Hygorphilas are usually quite sensitive.

Other possible signs are increased redness in your plants (those that will turn red). Thats usually indicative of low levels of nitrate... before it gets deficient.

[eric_kclee]

Bought an NO3 test kit from Sera for $15

Always show 0 ppm NO3...even I added a few drops of Lushgro Aqua (which has NO3) into the test tube...still show 0ppm of NO3.....I think it is damn useless..

I think look at plant response better...they won't lie to you...

[] wasted $15 bucks

[bclee]

NO3 kits uses reductive method to test for NO3. I think if you add too much of other stuff (ie. Fe and other traces) there may be some interference with the test result (just a guess). Why not you test it on some KNO3 solution?

So far I find test kits (I use Sera NO3 kits ) give me valuable information (do not have to be 99.99% accurate) in my learning about fertilisation on planted tanks.

BC

[theodore]

Either you are not doing it right or the testkit is faulty/expired. My Sera testkit gave me pretty believable* results when I ran my tests on tap water and a solution I prepared using Ca(NO3)2.4H20, my choice of NO3 fertilization.

*I used the word "believable" and not "accurate" cos there is no way of me verifying the results using more precise lab equipment.

[vinz]

First check that you are doing it right.

These kits do expire. Try getting an exchange from the shop, but not for another NO3 test kit. Chances are the whole stock is expired or faulty due to bad storage.

[bttay]

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On 9/11/2003 2:09:27 AM

Bought an NO3 test kit from Sera for $15

Always show 0 ppm NO3...even I added a few drops of Lushgro Aqua (which has NO3) into the test tube...still show 0ppm of NO3.....I think it is damn useless..

I think look at plant response better...they won't lie to you...

[] wasted $15 bucks
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Eric, I use Sera NO3 test kit too. But when I added a bit of Dr. Mallick's KNO3, into 1L water, I get result. Maybe the Lushgro Aqua does not content a lot of NO3 to give you the indicative color?

[eric_kclee]

Unfortunately, I don't have any other source of NO3 (not KNO3)

er...if buy 1kg of salt to proof the test kits will loose few more $$....I think better not....also don't know how to convince the shop that it is faulty.....somemore opened and used already...not easy to return.....no choice loh...

Thanks for all the response.

[squall99e]

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On 9/11/2003 2:09:27 AM

Always show 0 ppm NO3...even I added a few drops of Lushgro Aqua (which has NO3) into the test tube...still show 0ppm of NO3.....I think it is damn useless..

[] wasted $15 bucks
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I used to have problem with my sera NO3 test kit getting different test results with the same water. Buy another sera NO3 kit, 2nd one give constant result.
1st one powder stick together and dark grey (spoil)
2nd fine powdery form n light grey