urbionic

Hi all

I'm experiencing some calcium and potassium deficiency in my natural setup. The local water supply (Western-Cape, South Africa) is very soft and similar to rain-water as it contains almost no macro/micro nutrients. My question is how would I be able to solve this problem in a natural setup with limited water changes. I'm not sure how or what I should dose and how this would affect my tank. Symptoms showing in my hygrophylia polsysperma: older leaves have pin-holes and are turning yellowish, new leaves are misformed and curling. Any suggestions?

Thanks,
urbionic

Carissa1

Calcium - you can add crushed shells or coral to the substrate to rectify this. I'm not so sure about potassium, the only thing I know of is to add potassium sulfate to the water.

Endler Guy

I second Carissa on the calcium. It could take time to leach out so if you need a quick fix, you could dissolve a couple tablets of calcium carbonate antacid. If you do this, add it slowly over the course of a couple days. It will raise your pH and KH. If you need magnesium along with the calcium, you could add emsom salt.

For the potassium, you can use a salt substitute. In the US it's called No Salt. Make sure it's pure potassium chloride. I'm not sure about dosing but I've read that's it's pretty hard to overdose on K. If you have a low KH, you could get a hold of some potassium bicarbonate but the shells or coral should take care of that. If you do add the potassium bicarbonate, add slowly as with the calcium carbonate.

You can get two ferts in one if you get potassium nitrate or potassium phosphate but fish food contains a lot of nitrogen and phosphorous. Just some options for you.

Over the long haul, shells and/or coral should suffice for the calcium. A month's worth of fish food should contain 3 months worth of K (Diana's book p. 80). So, I'd assume you wouldn't need any more ferts than the initial correction. If it's the new tank, you'll probably have built up a sufficient microbial community, which will break down and liberate the potassium in fish food/mulm, before the initial dose is depleted.