The Planted Tank Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
14 Posts
Discussion Starter · #1 ·
So after installing a super bright LED lamp, my plants began to bubble. I was glad. Now they are developing symptoms consistent with potassium deficiency. Stunted growth, tiny holes in leaves and the presence of Green Spot Algae. I've looked everywhere and I couldn't find a source of potassium. Of course I can always buy Flourish but since it's imported, the price is a bit stupid. So I have began looking at alternatives found from the garden centre.

Question is, can I use these?



or this?

 

Attachments

·
Registered
Joined
·
2,105 Posts
Possibly. You would need to list the analysis and ingredients (maybe listed as "derived from"). Without that information it's impossible to say for sure.
 

·
Registered
Joined
·
14 Posts
Discussion Starter · #3 ·
Possibly. You would need to list the analysis and ingredients (maybe listed as "derived from"). Without that information it's impossible to say for sure.
For the potash, it simply states Potassium as citrate. Whatever that means. However for the NPK fert, it seems safe enough since other aquarist has used it. However, will N15 and P5 be too much nitrogen and phosphorus?

5 grams of that stuff will give me 30ppm of K and 15ppm of N and 5ppm of P 5ppm.

Some websites say optimal P should be 4max. So i'm a bit concerned about this.
 

·
Registered
Joined
·
2,339 Posts
So, regarding the first fertilizer, some things to watch out for in general when trying to use land-gardening fertilizers in aquariums...

Nitrogen - many land-fertilizers use ammonium or urea as a nitrogen source. This is fine for land plants, but ammonia is toxic to fish and forms readily from ammonium depending in pH (Urea slowly degrades to ammonium/ammonia). They can be used in very small amounts, or in slow-release encapsulated beads (ie: osmocote+). Use with great caution..


Micronutrients - Some land-plant fertilizers use sulfate rather than chelated forms of metals.. Sulfate forms of most metals are toxic to fish except in very small amounts, and are highly toxic to inverts in even minute traces. I would avoid using fertilizers containing copper sulfate, zinc sulfate, etc. You want to see these metals in EDTA or similar chelated form, which gives them a broader safety margin.
 

·
Registered
Joined
·
242 Posts
I've looked everywhere and I couldn't find a source of potassium.
I was able to get potassium carbonate from a local clay-pottery arts studio, very cheap close to five lbs for $10. I use 10x more potassium (on a weight basis) in my tanks than nitrate, as it seems to be consumed much faster than nitrate.
 

·
Registered
Joined
·
11,721 Posts
Potassium carbonate will also raise the KH. This is OK if you need to do this.

Potassium bicarbonate is another possible source of potassium, but it also raised the KH.

Somewhere (perhaps here at TPT) I read that potassium bicarbonate was a better source than potassium carbonate for aquarium use.
 
1 - 7 of 7 Posts
Top