Hygrophila sp. chai is a mutation of Hygrophila araguaia that occurred in South Island's farm (Singapore). It takes on a distinctively pink coloration, with occasional white streaks. The growth form is similar to Hygrophila araguaia - it is a stem plant but creeps along the substrate when lighting levels are high. It is generally very slow growing and sensitive.
The older leaves are very vulnerable to algae and thus this plant requires a very clean tank to grow well. Gentle water flow, strong CO2 injection and bright light accelerate growth. The difficulty it thus balancing an algae free tank while using high amounts of light. The samples grown on this page are under 200 umols of PAR. Tank instabilities and dips in CO2/nutrient levels also results in loss of older leaves, hence to have a larger bunch of it, tank conditions must be maintained in optimal ranges for an extended period of time.
The picture above shows the relative size & color of Hygrophila sp. chai in comparison to other plants. Information about this species is hardly complete since so few aquarists propagate it successfully.
Converting it from tissue culture format (which is the form in which it is most commonly sold) is the first hurdle. The TC is very delicate as a whole. It should be planted in matured, clean soil - excessive organic waste causes melting very easily. Good gaseous exchange is essential - this means flowing water, good oxygen and carbon dioxide levels. For this reason some folks find success floating it in the initial week to get some root growth; some of the TC samples can be very short, making it hard to plant. It also seems to favour quite a bit of light. In my farm tank example, substrate PAR levels is around 200 umols.
Hardcore enthusiasts may consider setting up a shallower cultivation tank where gaseous exchange and light access is generally better.
During the growth stage, it is very slow growing and will be shaded / over-crowded by surrounding plants. Hygrophila sp. chai grows more prostrate when the surrounding area is cleared.
It is important to keep the area around it unobstructed. Once it reaches a certain size, it becomes much more stable, and will grow steadily, but slowly. The main parameters to maintain is high CO2 levels with good flow, unimpeded access to light.
Under stress, fluctuating or unstable growth conditions, it is not uncommon for Hygrophila sp chai to spawn brownish leaves typical of Hygrophila araguaia. If there is only a couple of offending leaves, pick them off and let the plant continue spawning pink leaves.
If many leaves revert to brown, it is a sign that growth conditions in the tank are not ideal. This could be due to being a wide range of reasons; irregular CO2/nutrients, disturbances to planted area, algae etc. Anecdotal evidence suggests higher KH levels seem to trigger it - the plant does better in very soft water.