# Pottasium Questions



## AverageWhiteBloke (3 Nov 2014)

Not often discussed, how important is potassium?
Kno3 and po4 are obviously the most consumed in a thriving tank, magnesium seems to be as long as there's some same as traces but potassium you don't hear much about. 

I noticed that on a calc and on Clives EI article 30ppm a week is recommended which seems pretty much covered by the K in the kno3 and po4, well just shy actually. But in a situation where you were reducing kno3 and po4 would you supplement with more K or assume that using less of the others by default also means less demand on K and the whole thing being decreased pro rata?

Does less demand of one mean a less demand for all generally?


----------



## darren636 (3 Nov 2014)

Just Google potassium in plants.
Its pretty vital to food crops, I doubt its any less so in aquarium plants.


----------



## AverageWhiteBloke (3 Nov 2014)

Yeah I've been doing a bit of googling on it  I think it stems back to old days when I read "if you're going to add one salt, then go for K" obviously this would be in a low light situation where you might get away without additional po4 and kno3.
Just wondering if reducing the kno3 and po4 hence also reducing k would it be wise to maintain the level of K or let them all drop slightly by a similar amount?


----------



## parotet (3 Nov 2014)

Nearly everything has already been seriously discussed in this forum, that is why I love it. 
Want to dive into K secrets? Here you have:

http://www.ukaps.org/forum/threads/excess-of-k-na-ca-mg-fact-or-myth.25946/

It deals with other issues but it worth to read it.

Jordi


----------



## Jose (3 Nov 2014)

If you reduce the KNO3 and K3PO4 dosing to reduce phosphates and nitrates, then K is also going to be lower but, in your tank fish poo adds phosphates and nitrates and not so much K. If I keep a low tech tank with high enough bioload (for P and N) I would only dose K which you are not getting from anywhere for example, although the ideal would be to dose a bit of everything.

If you are running a high tech with 50% weekly water changes then there is no need to dose lower than EI though.


----------



## AverageWhiteBloke (3 Nov 2014)

parotet said:


> Nearly everything has already been seriously discussed in this forum, that is why I love it.
> Want to dive into K secrets? Here you have:
> 
> http://www.ukaps.org/forum/threads/excess-of-k-na-ca-mg-fact-or-myth.25946/
> ...


Thanks for the link although after reading the main jist of it appears to be how excess K affects plants, or doesn't' it would appear 



> If you are running a high tech with 50% weekly water changes then there is no need to dose lower than EI though.



I'm just having a little experiment trying to find a balance of TDS. My tank is lit with T8 at about 2wpg. Assuming EI is based on high lighting in the region of 5 wpg and still providing an excess to be on the safe side I assume I'm in a position to slightly reduce my dosing. At the moment I have softwater Amazonian species in the tank and the tank is about 250 ppm tds. Doing a 50% water change weekly and dosing EI means my tds creeps up a little bit at a time every week until eventually I do two 50% wc in one week. All good and well if I have the time. Ideally I would want to run the tank between 150 and 200 as the fish appear to be happier and there's plenty of spawning activity at these levels.

My TDS just before WC weekly goes like this 197 /229/ 243 after the water change the TDS lowers by about 50ppm. Wondering if, considering I have a bit of wiggle room on the dosing I could reduce the amount of salts going into the tank via unnecessary dosing of EI and I can somehow find a balance of what the tank needs without going into excess.

Common sense answer is do more water changes to lower the TDS and carry on with my current dosing but that's time consuming. So, back to the original question I guess is if I reduce the amount of po4 and kno3 would it be wise to still maintain EI levels of K or reduce everything?

I dose premixed in a 20ml syringe so my plan was to reduce by a mil a month until I see some negative effect.


----------



## Jose (3 Nov 2014)

The answer is: no one can know mate. What Tom Barr suggests is adding less over a time frame untill you see a negative impact on plants or get algae and then you can dose that last ammount. I dont really like this method cause your plant mass is changing all the time, and so is your uptake. I guess you have low-medium light so you probably wont run into problems but I dont know. Give it a try.

By the way it seems your tap water has around 200 TDS reading right? You wont be able to go lower than this unless you use RO water.

Oh sorry. You can do both things. If you add K to EI dose then you get more conductivity. Or you can just add what comes with nitrates and phosphates. Basically you are asking what the consumption of your tank is and no one knows. Its ttrial and error.

I wouldnt really add more K because you are doing a lot of water changes which will probably keep the P and N low.

But this could be wrong since I dont even know if you use a fertile substrate.


----------



## AverageWhiteBloke (3 Nov 2014)

No mate my tapwater is very low in TDS. I can't actually remember but I think it's in the 40's. I know you can't measure it with standard kh/gh drop tests so both are below half deg.


----------



## Jose (3 Nov 2014)

Oh ok. Lucky you! Mine goes cloudy in an aquarium after a couple of days due to carbonates. You could even breed cardinals in that water then.


----------



## ian_m (3 Nov 2014)

AverageWhiteBloke said:


> My tank is lit with T8 at about 2wpg.


Are you sure, its is not really possible to get this level of light from T8, which is why T5 and T5 HO are used. (unless you are usingT8 over a 7inch deep tank ). The WPG is T5 watts per US gallon, T8 are possibly 50% less efficient, see chart below.

Chart below from http://www.plantedtank.net/forums/showthread.php?t=105774


----------



## AverageWhiteBloke (3 Nov 2014)

Just correcting my previous post. The water change actually reduces the TDS down by slightly more than 50. The test was carried out after the magnesium and first dose of kno3 and po4 was added as I add these during the WC so I guess that would be roughly another 15ppm. The water change reduces by about 65 then the dosing raises it for the week about. 63.5ppm based on the below which my dosing is tailored to.

Nitrate (NO3) 20ppm per week
Potassium (K) 30ppm per week
Phosphate (PO4) 3ppm per week
Magnesium (Mg) 10ppm per week
Iron (Fe) 0.5ppm per week 

The rest of the increase I assume being from some stone I have in there and waste products. Considering I am most likely over the top with my ferts to be on the safe side there may be a little room to manoeuvre with the salts. If I can find a sweet spot then hopefully each wc will reduce the total TDS without affecting the plants.



> Are you sure, its is not really possible to get this level of light from T8, which is why T5 and T5 HO are used. (unless you are usingT8 over a 7inch deep tank ). The WPG is T5 watts per US gallon, T8 are possibly 50% less efficient, see chart below.



Sorry, I should have been clearer. I have 3xT8 2x25watt and 1x20. Going off that chart I guestimate about 20 par per tube which puts me in medium lighting.


----------



## Jose (3 Nov 2014)

Yeap go for it. But keep your eyes open for CO2 algae etc.


----------



## AverageWhiteBloke (3 Nov 2014)

I already run my co2 around the 40/50ppm KH 3/3.5 dropped to 6.2 from 7.0 Lime green DC (I know rough science ) and have no co2 related issues. So it should be a case of like you say monitoring for any algae or deficiencies in the plants. To be honest I was so obsessed with making sure I have plenty of everything that after seeing a while back the graph Ian-M posted above I wondered what the point was 

However, it hasn't done any harm practising on a tank that was probably a bit more forgiving lighting wise and it hasn't done the tank any harm either. All good experience for whenever I try out a high lighting tank.


----------



## Jose (3 Nov 2014)

Just out of curiosity. Dou you keep some sensitive shrimp in there or something? Cause a TDS of 300 is perfectly fin as long as its not from pollution (ammonia).


----------



## AverageWhiteBloke (3 Nov 2014)

I have Rams, neons and Panda Corys. The Rams are the most sensitive.


----------



## Jose (3 Nov 2014)

Yeap Rams are pretty sensitive. I am planning a tank for them. Maybe only with floating plants.


----------



## ceg4048 (3 Nov 2014)

AverageWhiteBloke said:


> Not often discussed, how important is potassium?


Potassium is the 4th most important of all elements. The importance is in this order: C->N->P->K.
Read more here: http://www.ukaps.org/forum/threads/lack-of-potassium.3516/

You do not have to worry as much about K as you do, for example about C, N or P. Plants accumulate K and therefore a wide range of K values can be used. Obviously, Klingons using unauthorized megawattage weaponology have to worry more so than humans of The Federation.

Cheers,


----------



## AverageWhiteBloke (3 Nov 2014)

As cryptic as the answer was, the end bit anyway regarding my low light human federation tank it's answered my question cheers. 
I would say reading your linked post that my quote about plumping for one nutrient then go for K is probably down to early day stuff when most ferts were trace only and the n and p came from fish/ biological waste. Supplementing k would help plants to utilise what was available.  

In my case just having some is probably enough within the kno3 and po4. I doubt I'm ever going to be putting in that small of an amount that K will become an issue. Not until I get my hands on one of them klingon heavy wattage guns anyway. 

For the best anyway. Defeats my plan of reducing Tds if I'm reducing the n and p then adding k just in case. Noticed it seems to take a lot of it to increase k by a little.


----------



## AverageWhiteBloke (3 Nov 2014)

> The WPG is T5 watts per US gallon, T8 are possibly 50% less efficient, see chart below.



Is this right? Based on T8 70 watts over 35 gallon and my par being about 60 the numbers stack up both at medium lighting. Convert that to T5 and in Wpg and that's a phenomenal amount of par! Zi would say you could get a suntan at the 5wpg limiting light theory EI based on. 

That being the case I have even more wiggle room while dosing EI. I don't even think I'll wait for a bad reaction. If I hit a point where the tds is not rising I'll stop there and if manage to get there without inducing algae, bonus.  

The extra 50% wc can be done at leisure.


----------



## Jose (4 Nov 2014)

It doesnt matter weather you have T5s or T8s, all that matters is PAR. You can have an X amount of PAR with both, but you will need more T8s. So your lights ought to be just right so as to be able to take actions in time.

Also in theory, and if you dont have other imputs for TDS, EI dosing in the long term will keep your TDS at a nearly constant value (at the end of the week) if you dose the same every time no matter how much you dose.
The ppm of ferts wont ever go over double the amount you dose in a week if you do water changes of 50% a week.


----------

