Dosing Pottasium Sulphate

[ricardo48]

Anyone have much experience dosing this?


Im following EI dosing on a 15 gallon tank and according to www.aquaessentials.co.uk

I have to dose 40ml of my 500ml solution per 100 litre of water x3 a week.

For me this works out at 25 ml x3 a week.

I mixed 55g with 500ml to make my solution as per instructions on website.

Target range is 20ppm but this still seems alot of dosing?

 

[mgamer20o0]

you test the water then add then see where it is.

 

[ricardo48]

Thought point of EI dosing is its estimative so you dont use test kits?

Just wanted rough idea if adding 25ml seems alot for tri-week dosing?

 

[mgamer20o0]

there is no set standard in liquid ferts. so how are we to know how much Pottasium Sulphate is in it?

the point of EI is to start off to make sure you have all the ferts your plants could possibly need then reset each week with a 50% water change.

only way to know if it is a lot is dump it in the tank and see how much shows up on the nitrate test kit. wait a couple days and test again to see how much of that said fert you put in used up.

 

[jsoong]

He is dosing Sulfates! There is no SO4 test kit that I know of .... <Unless you are actually dosing KNO3 & the "sulphate" is a typo?>

He also stated the concentration is 55 g in 500 ml. If you are dosing 25 ml of that, that is ~2.5g per dose. That actually is ~20 ppm of K & SO4 added per dose. the actual level depends on how much your plants had used up. <But the point of EI is you overdose so the plants have everything, and the theoretical max level if you do the 50% weekly reset is 2x dosed, so your max would be 120 ppm.>

That is an awful lot of Sulfur <OK level for K>. I know people do use K2SO4 to dose potassium, but I personally think KNO3 makes more sense, as you will need the nitrates for the plants, so why not kill 2 birds with one stone.

 

[ricardo48]

I am dosing kno3 also and im doing p04.

 

[jsoong]

How much KNO3 are you dosing? That plus the K2SO4 could be overkill in the K department.

 

[ricardo48]

Was always told you cant really over dose K unless its like way over 100ppm or something??

Im adding 5ppm of Kno3 per dose and 20ppm per dose of normal K2so4.

Im following all instructions as per EI dosing schedule so assumed was ok?

Should i cut K2so4 down to 15ml per dose?

 

[jsoong]

That is a very low dose of NO3. Unless you have some other source of N, I would think that this is an unbalanced regime.

Normally, the aim is for ~20 ppm of NO3 & 20 ppm of K.

If you are using KNO3, 20 ppm of NO3 goes with 15 ppm of K, so you add ~5 ppm of K2SO4 to make up for the rest of the K needed.

You seem to have the KNO3 & K2SO4 dose reversed. Just look at those, you are adding 5 of NO3 & ~23 of K. It is an imbalance. The K won't be harmful, but it is wasteful. And I don't know what all that SO4 will do. <Normal S requirement is only like 2-3% of N)

This is a nice dosing regime:
EI light: for those less techy folks - Aquarium Plants - Barr Report

Those are the "dry" dosing rate. You can convert that to solutions if you like.

 

[ricardo48]

Im confused. I followed instructions on Chuck website and www.aquaessentials.co.uk

Target level for Nitrate is 5ppm. I add 6ml 3 times a week. Each 6 ml gives me 5.16ppm of nitrate.

Potassium is target of 20ppm... each 25ml dose gives me 21.75ppm.


so my dosage is spot on to meet EI dosing?? I confirmed this with checking using Chucks calculator for planted aquarium.

Anyway im slightly heavily stocked with fish which contribute towards my nitrate also.

Im starting to get GDA but was told this is more to do with phosphate and co2 than anything else.

 

[jsoong]

5 ppm target for nitrate seems rather low to me. <I get really bad BBA if I ever let the N get that low.>

Many here go by Greg Watson's method & the target levels are N - 20, P - 2, K -20. The general guide in EI is to dose 1/2 that amount daily or every other day. <And you can fine tune things a bit if you want by measuring the NO3 level to see how fast the plants are using that up.>

N is one of the major nutrients & restricting that seems counter productive. Most here find that a level of 10-20 to be minimum when target dosing, and if you are doing EI, you are supposed to be overdosing. Although excess K doesn't seem to cause problems, plants are not going to be able to use the K if N or P is deficient. <BTW, when you are calculating how much K you are adding, you need to count not just the K in the K2SO4, but also the K in your nitrate stock (KNO3) - the level is ~ 75% of the N level.>

 

[ricardo48]

Ok.

I re calculated some formulas and changed the following.

I have changed my k2so4 dosing to 15ml x3 a week instead of 25ml

I have increased kno3 to 12ml x3 a week instead of 6ml.

This is giving me 10ppm per dose of N and with my high bioload should maintain sufficient N

I reduced my K to compensate for the K added when dosing my kno3.


Thanks for your help Jsoong... will keep you updated if it makes things better/worse.

Main problem I have is GDA, mainly on my brazilian pennywort and mainly on leaves nearer surface.

Is my 2x24 watts of T5HO too high lighting for my 15 gallon tank? I do have a constant 30-40ppm co2.

 

[jsoong]

That is a high light tank, but should be OK with CO2 & ferts.

A lot of times it is a bit of trial & error to find out what your plants need & dose accordingly. You can alway measure the NO3 to see if it is bottoming out. <OK, this is not in the spirit of EI, but I like to peek & see what the levels are at & how close the estimates are! > If it is close to zero between doses, you will need more. <High light & high growth can bottom out nutrients.> Having NO3 bottoming out can bring on some algae (the N-fixing ones like BBA.)

 

[ricardo48]

Ok... well all i have at moment is GDA and mainly at surface of the tank on my pennywort leaves. I was told to leave this to live out its life cycle for 3 weeks? Then it will go

 

[timwag2001]

i think its best to remover the leaves that have algae on it.
did you say you were dosing po4? how? what are you using?

 

[ricardo48]

P04 is coming from my dry fert mix i made up.

Algae has got alot better now.... i have started to get some thread algae manly growing on large chunks of laterite I have in my gravel, wonder if they are feeding it somehow?

 

[Ruadh]

I've seen where, several times, Tomm Barr has stated that the 5 ppm in Chucks Calculater is a mis-print and should be 50 ppm.

Im confused. I followed instructions on Chuck website and www.aquaessentials.co.uk

Target level for Nitrate is 5ppm. I add 6ml 3 times a week. Each 6 ml gives me 5.16ppm of nitrate.

Potassium is target of 20ppm... each 25ml dose gives me 21.75ppm.


so my dosage is spot on to meet EI dosing?? I confirmed this with checking using Chucks calculator for planted aquarium.

Anyway im slightly heavily stocked with fish which contribute towards my nitrate also.

Im starting to get GDA but was told this is more to do with phosphate and co2 than anything else.

 

[timwag2001]

if you are mixing kh2po4 you are dosing k with that also. and if you are using kh2po4 and kno3 you prob dont need k2so4.

also i would stop using chucks calculator. i've found a few mistakes myself. i like Aquatic Plant Central

 

[ricardo48]

Can anyone else confirm if you are EI dosing Nitrate is it best to aim for 50ppm as you want excess nitrates?

 

[Ruadh]

Depends on how many plants you've got.
My tank is moderately plants and 50-60 ppm is where I keep it.
You'd do well to go to Aquatic Plant Central and also Tom Barr's site and read up.
There's a lot of people there who have a lot of knowledge they actually love to share.