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Dripping Potassium & Iron

Discussion in 'Advanced Topics' started by Turbo, Mar 19, 2015.

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  1. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    So, I was at our club's Spring Fest a few weekends ago and I had a great discussion with one of the speakers afterwards (Justin Credabel) regarding the role of Potassium in the reef aquarium. His presentation was mainly related to Goniopora species and I didn't get a chance to hear all of it, but when I heard him talking about K my ears perked up so I grabbed him afterwards.

    Basically, he told me that it's pretty hard to OD on K. He has ran tanks at 900-1000ppm and seen no negative side effects (400 is NSW). He also mentioned that negative effects can start to show up when you get into the mid to low 300s. Scrubbers suck K down like a 10 year old sucks down a shake from McDs. Trying to keep K and 400 in a scrubbed tank can be a challenge but I haven't worried too much about it as I really didn't see any negatives when running K at 350 or less even...but that doesn't mean I should be running it there.

    I use the Salifert Potassium (K) test kit. Very easy, fairly accurate. I've heard that the kits in general are good for noting differences from one test to another, but that the accuracy of the reading itself might not be the greatest. What that means is if you test one time and get 400, and the next you get 370, you can be sure that your K dropped 30ppm but your readings of 400 and 370 might be off (but equally off). So you might have 410 and 380, or 390 and 360. End of lesson.

    Now, as for K dosing, he runs a constant drip. Now that makes me say "dang bro you must have extra cash laying around" because even buying Brightwell Potassion-P, which is powdered concentrated K, is expensive considering the amount you have to dose just to maintain 400ppm.

    He told me however that he uses Morton Potassium Chloride in bulk bags. The downside is that it has Phophates, not a ton, but some. He mixes it up in a bucket, and says that the chloride offgasses so you aren't throwing off the ionic balance by dosing it. Not sure it all offgasses, but that's irrelevant as you will shortly see. Then he drips it into the tank through GFO and this takes out the phosphates. I thought, dang, that's awesome.

    Next, he says that he also drips Iron Sulfide. So I'm thinking, Iron Sulfide + Potassium Chloride, no problems with ionic balance, and you get K and Fe, both good for tanks, corals, scrubbers, etc. Win Win Win. I'm not sure on the source for Fe but I'm going to find out.

    Iron is highly reactive in the reef tank and get depleted out nearly immediately. It's hard to OD Iron. He explained the mechanism to me and it's gone, it's been a week or so and I've forgotten most of the discussion but there is a mechanism as work that reduces Phosphate out of the water column very quickly when dosing Fe and I believe K also.

    The point here is though that when using an algae scrubber in a high K environment, the excess K will cause algae growth to pull N and P out of the water column faster.

    The result?

    Supercharged Algae Scrubber. Possible reduction in the "clean-up" time in a dirty tank. Possible method of fueling an algae scrubber in order to out-compete tank algae (think dripping Fe and K at the scrubber input). Possible method of faster reduction in water column nutrients in a neglected tank. Possible solution to N=0 but P still present in water column.

    So this is kind of a big breakthrough that I still need to research and gather info on, but I wanted to start this thread and open this up to the tech heads and chemical geeks who have more time than I do. I'll be in touch with Justin for some more clarification as well.

  2. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    So I heard back from Justin.

    He uses the Morton stuff


    They even have a product finder...unfortunately, where it says I can get it - Wal-mart - doesn't stock it and can't ship it. Hmmmph. It's probably only $50 for a 40lb bag too.

    Anyways, you mix this up into solution then let it sit for an hour to offgas the chlorine. My guess is that you don't want to do this in a closed space as chlorine is bad. After an hour, you can dose.

    I'm not sure on the dosing regimen but once that is figured up, raise levels by 20-30 ppm per day, and running between 550 and 700 ppm is fine.

    Drip the solution through dry GFO, just dripping through a plastic cup is fine - nothing fancy needed. Keep it simple.

    For the Iron Sulfate, use the Randy Holmes-Farley recipe, which I found in this thread:


    Which appears to be the most recent based on the first 2 posts of the thread

  3. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    No Morton near me, but my water softener guy said it's all the same. Scored a 49 lb bag at the Depot for $24
  4. Matt Berry

    Matt Berry Active Member Trusted Member

    That's a lot of potassium :eek:, cheap though.
    Are you going to test it out to see if you get stronger growth dosing potassium and iron?
  5. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    That's the idea. Really what I personally was aiming for was a cheaper dosing product.

    But, the potential here is that if someone has a neglected tank with high N and P, getting a scrubber going and then (once the screen is maturing) starting to does Fe and K can do 2 things: first, Iron is highly reactive and tends to bind to many thing (I believe P is one of these but I can't recall what he said) and then both Fe and K will boost macro growth, meaning a faster green screen, and that leads to faster nutrient absorption. So instead of needing a bigger scrubber, or more units, one could just supercharge their current scrubber and speed up the clean-up process.
  6. Matt Berry

    Matt Berry Active Member Trusted Member

    Since you said iron and potassium is pretty hard to overdose, I guess a dosing ratio could worked out once we know approximately the algae uptake of K and FE? Would be good to avoid people having to buy test kits. The ratio would be based on the scrubber size, as opposed to the size of the tank right?
  7. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    Iron test kits are a waste of $$ for SW according to just about everything I've read. Hard to overdose, unless you're SM and dump a half gallon into a 90 gallon tank (which he did)

    Potassium is hard to OD also I guess, as long as you don't raise it too fast and that would be the main key I think. Justin said he's ran K at nearly 1000ppm and noticed no negative side effects
  8. acorral

    acorral Member Customer

    I have kept potassium at 400 but today I started dosing directly ti the input of the scrubber... The initial test is to drip the KCl needed to rise 50 ppm of potassium in 5 days... Two days ago was my last screen cleaning so I expect this potassium to run through the scrubber the rest of the week to have sort of a turbo scrubbing week...

    On the iron side as you said... Testing is useless so I will just dump some iron supplement to make sure it is not the limiting factor...

    Let you know my observations later...
  9. Just a few notes.

    Chloride isn't chlorine and does not 'offgas'. Otherwise dosing calcium chloride would not raise chloride in our aquariums, but it does, Randy Holmes-Farley's 2-part article discusses this. :)

    Be very careful with KCl. It is deadly to fish and invertebrates if not properly dissolved or overdosed. A few months back I dosed around 15 tablespoons of straight Potassion-P powder (which is not even lab-grade concentration) and suffered extreme fish and invertebrate loss. This was done in error due to a miscalculation, I was doing this as an experiment to see what was too fast, what was too much, and I definitely got my results once I realized my error, losing some fish and inverts that had been with me for several years. This past Tuesday I decided to try dosing again, and I lost a dozen fish to dosing after dissolving two tablespoons (approximately 15 grams) in one liter of water and dosing it about 10 minutes later. This would have raised the K level in my tank by only ~21ppm, so while considered a 'safe' dose, it wasn't very much so since it was not very well dissolved.

    No corals or anemones were affected with either dose, other than a significant increase in pigmentation in my maxi-mini anemones. They bleached a few months ago along with some palythoa, and after a few days of this K dosing regime they not only regained their initial pigmentation but have far surpassed it. No other changes have occurred in the tank.

    I took my scrubber screen out of the tank at the end of February trying to identify an increase in gelbstoff in my reef that was significantly reducing water clarity (despite using a large skimmer, a cup of ROX 0.8 carbon, and nearly 600mL of Purigen). After a few weeks, I noticed that the water had not cleared any amount, but I had not noticed any other changes in the tank due to the scrubber's absence (despite still feeding enormous amounts per day), so I have not yet added it back in, partly from laziness lol.

    This tank has seen basically no water changes, so if the scrubber was actively removing large amounts of K, then I would have been severely deficient, explaining why the anemones and corals had poor color, especially in blue and purple, so dosing K definitely made sense.

    More of the story is just to take it easy and ensure that your solution is very well-dissolved before dosing. :)
  10. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    You need to check something, did you mean teaspoons? I went a round with Brightwell about this and to my knowledge they still haven't updated their label.

    1 tsp = 7.5g
    1 Tbsp = 3 tsp = 22.5g

    So 2 Tbps would be 45g not 15g.

    I recall we discussed this in another thread so I assume you weighed it before mixing? This could affect the dosage meaning you could have bumped K up 60ppm not 20.

    I've mixed according to the directions (tsp not weight) and ended up with a triple-strength solution, but I never had any problems dosing that.
  11. No, tablespoons, teaspoons are for pansies ;)

    I remember discussing it with you when it happened the first time, that one was a pretty significant overdose. I remember weighing it last time and then my brain mixed together the two numbers and hence the miscalculation lol. For what little amount of testing the Salifert test kit gave me results for (it only goes up to 470ppm), the stock solution according to the directions was a bit higher than what it says, but not by too much. Maybe they've just had consistency issues? Either way, I'm looking at getting some lab-grade KCL and K2SO4 next.

    But yeah, the gist of it is to only dose a fully dissolved solution and still try not to overdo it. :)
  12. TbyZ

    TbyZ Member

    Interesting thread. I've been thinking about getting a potassium test kit to check my K, but I get v good green growth. What negative effects can occur in a reef T if K is low.
    I live right on the coast & can do weekly water changes using nsw, so I guess it shouldn't be an issue
  13. TbyZ

    TbyZ Member

    How much does the potassium level drop over a month in a scrubed tank?
  14. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    K is going to get taken up differently depending on your setup. Size of scrubber, tank volume, etc

    I've never really kept that much track of it. What I know is that you can drop it down pretty low and it will not go much lower than a certain point (which is probably some kind of limiting point I'm guessing)

    The more accurate way to get to the root of your question though (how much do you need to dose) is by figuring out how much you need to add in order to maintain a given level.

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