Elatine triandra and nitrates

To get my tank to recover, I am replanting the tank in phases. Starting about 4 weeks ago with Elatine triandra which is fondly known as Ah Pek Plant (APP) in Singapore. Once planted, the Elatine immediately flourished. Elatine is a very fast growing plant and is a nutrient hog. With lots of fertilisers (including CO2) and light, it grows very fast. At the same time, once fertilisers are lacking it melts very fast.

At the second week, I tested my NO3 just to see if it has reduced and it was still in the 40-80 ppm range. From the start of the tank till now, I’ve never had less than 20ppm NO3 in the tank even though I don’t dose NO3 except for a span of a few months last year.

By the third week, I had to trim the Elatine as they had started to overgrow my low rocks and looking rather unsightly.  Hopefully, trimming would encourage more side shoots and creeping growth rather than the upward growth till then. Algae on the glass had also noticeable reduced. But, I noticed that the old leaves were starting to yellow and melt. It was still minor, so I decided to just wait and watch. Maybe it’s just new tank syndrome? The symptoms indicated either N or P deficiency. I dose P, so that was eliminated. My tank supposedly has high N, so I disregarded that. I have already maxed the dissolution capability of my CO2 reactor, so that’s not option anymore… plus growth was excellent before, so can’t be CO2.

This last weekend, the fourth week, the Elatine looked really bad. Large patches had melted completely. This 2 days, they continue to melt…

I dose everything (P, K, CO2, trace and Fe) that the plants need to grow well, except N. So today I tested for NO3 again… lo and behold, ZERO nitrates! And it correlates with the symptoms of yellowing leaves melting from tip to stem. The Elatine sucked up all the NO3 that has been above the 20ppm range all this time in about 4 weeks.

Admittingly, I may have been an accomplice. In trying to fix things with the tank, I have in the last 2 months, progressively made major changes and done major cleaning in the tank:

  • Removed the white sand foreground.
  • Vacuumed and trimmed the algae infested plants, especially the big dirt trap mass of Java fern.

I further suspect that my tap water which used to come with about 20ppm NO3 may not have NO3 anymore. This needs testing to confirm.

Fortunately, I still have my NO3 solution in my cabinet and quickly made a dose. Let’s see what happens to the remaining Elatine in the coming weeks. It should recover quickly as it’s a very fast growing plant and I still have about 60% of the lawn still viable.

In the medium term, I will replace them with Staurogyne repens, but might keep a small patch as the proverbial “canary in a coal mine” for nutrient issues. It’ll be helpful as a indicator plant when the tank stabilises and I start tweaking my fertiliser dosages down.

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