• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

How much Potassium Phosphate (KH2PO4) for 300 litre heavy planted tank?

GlassWalker said:
The APF ferts state to dose 10ml per 50L, so as you're using the same concentration, that would be 60ml per dose.
Click to expand...

Yes that's right.I dose around there.

The reason I posted this question is due to a post in this forum where the member is dosing the below :

Macro mix
42g KNO3
15g KH2PO4
92g MGSO4
Mixed to 600ml water, dosing 50ml on alternate day for 200 Lt tank.

Since I dosing only 7.66 grams for a 300 lt tank, I'm thinking maybe I not dosing enough for my heavily planted tank.
Furthermore I have GSA on the rocks and plants. Isn't this due to shortage?
 
Given you have symptoms which could indicate phosphate shortage, certainly try increasing the dose and see if it helps.
 
Yes I know I have this shortage. But by how much? That's why I'm asking if the members here who have knowledge of EI method, on the amount of Potassium Phosphate I should dose for a 300lt tank. What is the ideal amount so that I don't have to add extra.
 
The point of EI is to have an excess, so you don't need to work out how much you need exactly, which may change anyway. Others with more experience here may be able to give indications but it does depend on the tank.
 
Please review the EI Tutorial http://www.ukaps.org/forum/threads/ei-dosing-using-dry-salts.1211/
which clearly suggests to add 1/16th teaspoon per 20 Gallons

300L can be rounded to 80G so simply multiply the suggested value by a factor of 4 = 1/4 teaspoon 3X per week.
This is the nominal dosing value but you can dose whatever you want, less or more depending on what you observe in the tank. This is the basic procedure. It does not need to be any more sophisticated than that.

Furthermore, as stated earlier, it is considered a waste of time and energy to fabricate mixtures for a tank of this size.

Just dump 1/4, 1/2 or a full teaspoon of this powder in the tank and get on with it. Do not make life more complicated than it already is.

Cheers,
 
ceg4048 said:
Please review the EI Tutorial http://www.ukaps.org/forum/threads/ei-dosing-using-dry-salts.1211/
which clearly suggests to add 1/16th teaspoon per 20 Gallons

300L can be rounded to 80G so simply multiply the suggested value by a factor of 4 = 1/4 teaspoon 3X per week.
This is the nominal dosing value but you can dose whatever you want, less or more depending on what you observe in the tank. This is the basic procedure. It does not need to be any more sophisticated than that.

Furthermore, as stated earlier, it is considered a waste of time and energy to fabricate mixtures for a tank of this size.

Just dump 1/4, 1/2 or a full teaspoon of this powder in the tank and get on with it. Do not make life more complicated than it already is.

Cheers,
Click to expand...

Hi Clive
Thanks for your reply. I'll study the link and your info.

I did try direct to tank method once. To my horror my Congo Tetras & Rummynose started / attempted to eat it. :p
 
I can't edit my previous post, but the reason why i would check PO4 as this will change in your tank lifetime. More plants, less plants, more light less light, clay soils etc.

From the photo you posted seems like you use clay soil in your tank. Many of these soils can suck up PO4 in the first few months or so.
In this time if you measure PO4 the level is very low or close to zero even with EI. So you start dosing KH2PO4 more and more as you need more PO4 to reach like 0.5ppm or 1ppm.
But things can change and the tank will fed up with PO4 and you keep dosing the same ammount this easily can lead to problems. Shrimp deaths, but even plant problems. We've seen a couple of times that Stautogyne Repens drop off all it's leaf because of this. Too high is 2-3ppm and above, which you easily can reach with powders.

So i would pick up a PO4 drop test. And would measure weekly later monthly the PO4. Just to have a better understanding how much really need for your plants.
 
viktorlantos said:
I can't edit my previous post, but the reason why i would check PO4 as this will change in your tank lifetime. More plants, less plants, more light less light, clay soils etc.

From the photo you posted seems like you use clay soil in your tank. Many of these soils can suck up PO4 in the first few months or so.
In this time if you measure PO4 the level is very low or close to zero even with EI. So you start dosing KH2PO4 more and more as you need more PO4 to reach like 0.5ppm or 1ppm.
But things can change and the tank will fed up with PO4 and you keep dosing the same ammount this easily can lead to problems. Shrimp deaths, but even plant problems. We've seen a couple of times that Stautogyne Repens drop off all it's leaf because of this. Too high is 2-3ppm and above, which you easily can reach with powders.

So i would pick up a PO4 drop test. And would measure weekly later monthly the PO4. Just to have a better understanding how much really need for your plants.
Click to expand...

Hi
Isn't "test kits" a taboo word in this forum. :hilarious: (Just kidding)

BTW my substrate is ADA Aqua soil only. Do you think the process which you described above will also occur with ADA Aqua soil? Please reply.

Just for info: I have GSA on the glass and plants and rocks:banghead:. So I'm currently dosing 3/4 teaspoon of potassium phosphate along with the normal dose 3x a week.

Cheers
 
GSA is related to any combination of poor PO4 + poor CO2. It's very easy to add more PO4 in order to see which is the culprit. However, if there are signs of poor CO2 elsewhere in the tank then that should be investigated. More than likely, if dosing EI levels of any nutrient, any signs of nutrient deficiency immediately indicates poor flow/distribution.

PO4 test kits cannot measure PO4. No one knows quite what they measure...
One can add any amount of PO4 without fear of consequence.

viktorlantos said:
We've seen a couple of times that Stautogyne Repens drop off all it's leaf because of this. Too high is 2-3ppm and above, which you easily can reach with powders.
Click to expand...
Leaves dropping of could only have been due to poor CO2. This was a typical misdiagnosis. Whenever you add more nutrients and observe a fault, it's telling you that you were underdosing something else. In the reported case, adding more PO4 exposed the fact that the CO2 was low. Adding more of any nutrient drives an upstream demand of other nutrients.
Here is S. repens where the weekly dosing was 10ppm. That was what was dosed, NOT what was measured by a silly test kit:
9633296392_a65d436bc1_b.jpg


Get over PO4 people. Embrace it.

Cheers,
 
Zak Rafik said:
BTW my substrate is ADA Aqua soil only. Do you think the process which you described above will also occur with ADA Aqua soil? Please reply.
Click to expand...

Yes, this affect most of the active soils we're using these days. Since we have more experience with Japanese soils (many of them) i only can tell these.

Zak Rafik said:
Just for info: I have GSA on the glass and plants and rocks:banghead:. So I'm currently dosing 3/4 teaspoon of potassium phosphate along with the normal dose 3x a week.
Click to expand...

Sometimes you can handle this with PO4, but there are times when you just can't. So need to check the light volume and timeframe you're using also the tank placement to any natural light in your room, plant positions (slow grower anubias can't be on top of the tank things like this).

You need cleaning crew too like Otocinclus or Neritina snails these handle nicely the algae.

Spoon is like bubble in a counter for me :) I agree test kits can lead you sometime to bad conclusions, but without knowing how much PO4 your tank has how do you know how much additional needed? :)
Most of the tanks are different. Even if i use the same light like you i may use a different brand which has more power. Other parameters could be different too. So to give a ballpark number of spoon is a great starter as it based on experiences, but sometimes worth to measure.

We also use KH2PO4 as an additional fertilizer to our daily routine with EI or ADA ferts sometime. Since we've seen many positive signs of using a little higher PO4 many guys started to use it too in our country.
So we've seen quite a few examples how KH2PO4 overdose can cause problems. Sometimes it will just not solve your algae issue, but will cause others.

If you're under 1ppm PO4 that's fine. With quick cure to go a little higher for a few days it's fine. But continous overdose above 3ppm will hurt.
 
ceg4048 said:
Leaves dropping of could only have been due to poor CO2. This was a typical misdiagnosis.
Click to expand...

I think sometimes there are other stuff on the plate. So meanwhile i accept your point of view, believe me we're on top of CO2.
This issue happened typically with external CO2 reactor injection where CO2 distribution never an issue. I only seen with staurogyne rep.(matured one not fresh planted one)
But then based on your 10ppm feedback above i may will do some additional tests to confirm it.

ceg4048 said:
NOT what was measured by a silly test kit:
Click to expand...

PO4 test kit silliness is new to me :) i know many tests fail or inaccurate or works differently in soft or hard water, but it was new to me :)
So no measure since there aren't anything we can use to measure just throw in and watch? :)
 
I think viktorlantos philosophy and ceg's are quite distant from each other. We are debating different techniques here. Both work. For one IMO test kits are not always useless (although many times they are) but on the other hand I dont ever use them so I can understand both point of views. I tend to agree more with ceg because in my experience test kits arent that useful.

Anyway to contribute the the first quistion here is a link to a good nutrient calc.
http://rota.la/
He's dosing 1.39 ppm of phosphates each time which is around 4ppm phosphates a week. This should be allright.
 
Last edited:
Hi Viktor,

viktorlantos said:
But then based on your 10ppm feedback above i may will do some additional tests to confirm it.
Click to expand...
Almost everyone thinks that they have CO2 beaten. I never assume this. I always assume that there is a CO2 issue just around the corner,

Adding nutrients drives a DEMAND for additional CO2 uptake, and adding CO2 drives a DEMAND for additional nutrient uptake.
So, while the CO2 may have been OK before you added the extra PO4, once you increase the consumption of PO4 the plant then needs more of everything, including Nitrogen. Increased Nitrogen uptake is a much easier problem to solve and you may not have even noticed the Nitrogen uptake increase because your sediment may have already been unlimited, however this would have then increased the CO2 uptake demand. If CO2 was not unlimited you would have crashed the barrier.

I routinely dose massive amounts of PO4 to the water column without any issue. Here is a very old thread showing the results of super massive PO4 dosing=> http://www.ukaps.org/forum/threads/blyxa-japonica-flowers-underwater.1967/


viktorlantos said:
So no measure since there aren't anything we can use to measure just throw in and watch? :)
Click to expand...
Well I suppose you could try to calibrate the kit, but honestly, PO4 test kits can only ever detect the presence of PO4, they can't tell you what the measured value is. It's exactly the same with NO3 test kits. They are easily fooled by other ions in the water column.

The thing is that apart from knowing what the tap water content is, which we can't really tell, if you are dosing a certain amount of the powder then it's very simple to calculate what you have added. So although you cannot account for the content added by the municipal supplier, or the amount added by food, you can easily calculate, with great accuracy, how much you have added if you are adding a salt like KH2PO4.

People get into trouble all the time assuming that the PO4 test kit is telling the truth, and in almost every case, the test kit over estimates the PO4 content, and they are so afraid of PO4 boogie man that they avoid adding PO4 which then causes more problems.

Cheers,
 
Yeah on the other hand 10ppm PO4 seems like crazy lot to me. Remind me Tom Barr's earlier comment years back about super high nitrate levels vs shrimps.
I could not quote exactly, but he mentioned like 2 or 3 times more NO3 than avg EI without any problems with his shrimps. He had zillions of CRS at that time.

My problem is that if a beginner reads that there are no negative effect of any of these things and test is a bad thing just use spoons no matter how your plants grows will lead to more problems.

I am not about test everything and make conclusions based on that, but sometimes tests can help. We're using JBL PO4 test kit or Sensitive Photometers depend on how much time we have :)

ceg4048 said:
Here is S. repens where the weekly dosing was 10ppm.
Click to expand...

Maybe i am wrong and the photo isn't that good, but looks like to me this is not a super high light tank. Why is that much fert needed?
From the photo it looks like to me a little slower tank with a little less light. Maybe i am wrong :)
 
You must log in or register to reply here.
Back
Top