Red_Rose

Can one overdose on K? I decided to do some searches on it and I came across a site(the Krib, I believe but I could be wrong) that said it's not really possible to overdose on K because it won't affect the plants. If that's the case then what about fish? Could that affect fish?

Just before anyone asks, no, I did not do this to any of my tanks. I do have a feeling that I under dosed though. :/

Thanks.

hooha

yes, it is possible to overdose potassium. I'd have to recheck, but from what I remember it can affect the utilization of Ca/Mg and lead to signs of deficiency of these nutrients.

What is your current fert regimen? If you notice some pinholes on the leaves of the plants, that may be a K defiency. You can supplement it, but make sure you do it slowly and wait at least a couple of weeks to see if there's any effect....

Red_Rose

I really don't have a regimen because my tank is an El Natural. A few months ago, I had noticed pinholes forming in my Crypt but at first, I thought it was the start of Crypt rot but it was very slow so after doing some research, I found out that it's from a K deficiency. Some of my H. polysperma have some pinholes in it as well.

It's been almost a month since I dosed the tank with KNO3 but I didn't use the full amount that was suggested to me(the amount I used was about 1/16 tsp that gave me 10ppm of nitrate). At the time, the plants were also showing signs of a nitrogen deficiency since my nitrates were at zero and have been that way for almost a year until I dosed the tank.

The plants have recovered from that but I do still have pinholes forming(although not as much as before) so about a week or so ago, I had gotten some K2SO4 and added slightly less then 1/8 tsp.

Do you think too much has been added? My plants have grown more since adding both potassiums to the tank.

hooha

Out of curiosity, how much light do you have on the tank?

As for the amount of potassium you're adding - how big is your tank?

Red_Rose

I knew I was forgetting to add info in that last post. Sorry about that.

I have a 10 gallon tank and I use two 10 watt CFL bulbs that I leave on for 10 hours every day and on most days through the Spring and Summer, the tank gets about 1-1.5 hours of morning sunlight as well.

I use the Dutch Nutrient Formula fertilizers from Homegrown Hydroponics if that's of any help.(I only have the K2SO4 and KNO3.)

hooha

that's ~ 9ppm of potassium - that should be fine for now. Do you plan on dosing nitrate and potassium regularly? if so how often?

Red_Rose

I've read that potassium levels should be anywhere from 10-25ppm. Would 9ppm be enough to stop the deficiency in my plants?

I have considered dosing regularly to prevent these deficiencies from coming back. I was thinking about dosing the K2SO4 once a month and the KNO3 will depend on how long it takes the plants to use up the nitrate. It's almost been a month since I last dosed the tank with the KNO3 and my nitrate reading(I tested it a few days ago) was around 7-8ppm. How does this sound to you?

hooha

I forget that you don't usually fertilize Potassium in your tank (through nitrate and phosphate). Personally, things run better for me if I dose smaller amounts more frequently. But I've never had to dose (so far) a soil-based tank.


If you would like a suggestion, I would try dosing 1/8 tsp of potassium sulfate and 1/16 potassium nitrate every 2 weeks and recheck your nitrate levels (provided that your test kit has been calibrated). That increases your nitrate by 5ppm and your potassium by 12ppm. Keep us updated on the results I would look to see you're getting more growth than pre-dosing and little algae outbreaks, with the nitrate levels being stable (~ 10ppm).

Red_Rose

Thank you for the suggestion. When it comes to things like this, I'm thankful for the help!

I have no problems dosing the potassium sulfate every two weeks but I'm not sure I'd want to do that with the potassium nitrate. At least not until the end of summer. In our city, there are several underground sources that we get our water from. Once section of the city might have a pH of 7.0 whereas our area is at 7.8. Normally, our water would have zero nitrates but because of the construction that going on on our street(it won't be completed until the end of summer), we are getting our water from a different area and that water has about 7-8ppm of nitrate in it. I think that's why my nitrate reading isn't going down quickly because whenever I top up the tank, the nitrates are being added back into it.

Because of this, should I still add the potassium nitrate every two weeks or should I just wait?

hooha

do you do any water changes or just top offs?

If you do water changes 1-2x/month dosing 10ppm (i.e. 1/8 tsp) of potassium sulfate every 2 weeks shouldn't be a problem. If you don't then 1/16th would be a safer number and increase in 4 weeks if you still see signs of defiency......at least that's how I would approach it