Node spacing doesn't indicate light being the cause unless you did something in that regard very recently.
Sounds like you don't have good watering habits.
1) fully saturate
2) wait for top inch to dry and repeat.
is the simples way to put it... 'enough' drayback is the key and you don't want any wilt, of course. The volume required will be similar if you irrigate at same loss of weight from the pot. You don't choose the volume nor the time between irrigations. Context dictates these things not some top-down feelings on the matter.
If not doing that, start. It may be the cause. Partial watering may be leaving certain zones of medium dry which can be difficult for roots that grew there and invites buildup of nutrients as moisture ebbs/flows around a dry pocket .. evaporation deposits more nutrients each time it happens, then goes back into solution when it gets moisture again etc... also, it trains superficial roots which are not ideal.
if watering entire volume ever causes a problem, it is 100% the fault of how the medium was constituted. Simply watering should never cause a problem (assumes you don't water too frequently).
Take your brain out of it. Simply react to what you observe. Give the volume necessary to accomplish the task and not some preordained volume you chose to give every 2 days.
If that is 'soilless' you need 10% runoff to maintain nutrient levels. In soil, just make sure it is fully saturated with minimal runoff when things are healthy - i.e. don't waste your soil's amendments. I'd suggest more perlite mixed in... 50% of volume for high water capacity soils and 30% of volume for coco coir context. Both end up with same drainage/aeration properties.