It’s like learning Greek and Latin roots in English class! If you know Photo means light, it’s easier to know what photosynthesis, photography, photosensitive etc means. (I’m an English teacher lolol).
I also never learned hanja for korean, and I just picked up the patterns over time 
Ok I am nowhere near an expert, and this is only my limited understanding of it:
So Korean as a language has existed for a very long time, but it didn’t use to have a writing system. So Koreans used hanja to write their own language - that being said, as you probably know, hanja isn’t the easiest way of writing so only the most privileged people could write. Anyway, at some point during the 15th century King Sejong created hangeul, which is as you said a phonetic alphabet still in use nowadays.
So that’s for the writing system.
As far a words go, I know even less 
but I do know that, much like most of Spanish words come from latin, a lot of Korean words were derived from Chinese. Except that the sounds in the Chinese language and the sounds of the Korean language don’t match, so the pronunciation is different.
So for example today I learned that 身 means old [EDIT: no it doesn’t. it means body haha oopsie). Now, in Chinese (according to wiktionary ) it is pronounced shēn, whereas in Korean it is pronounced sin. Not exactly the same, but similar.
Now how does that help with learning Korean? Well, now that I know that sin means old, if I ever come across a word I don’t know that contains sin, I know that it may have something to do with that meaning. Except, of course, there are a lot of hanja that are pronounced the same.
So yes, from my understanding knowing Chinese helps tremendously with learning Korean, but I am very much not learning Chinese. I am learning a few of the most common hanja - and even those I am not focusing on writing them out or recognising them, I just want to know their Korean pronunciation and meaning.
That’s a long winded answer, ddochii sumed it up very nicely 
Hanja will pop up occasionally. It’s something you’re likely to come across in a medical context, and I’ve seen it in translations of Japanese novels for example, just for clarification. Schools teach 1800 hanja, potentially more in university.
As a learner, it’s something that I wouldn’t necessarily consider essential, but it’s helpful to know. The key here is knowing the Korean pronunciation and associated meanings, so you’ll be able to infer the meaning of new words. It’s a bit similar to learning Latin or ancient Greek roots. Do you need to know that -vore is from the latin for eating/devouring to understand carnivore or omnivore? No, but say you come across amphibivore in a book, you can take an educated guess that the first part is probably related to amphibians… You now know what amphibivore means.
So it’s like that, except in Korean a lot of words are made up of hanja, including more basic words. I find that it’s also great for reading fantasy, because that’s basically a treasure trove of words you won’t find in a dictionary, and the main reason readers aren’t confused is that these are basically just words made up of hanja.
Oh that’s a nice tip about fantasy vocab! I never knew that. Yeah I guess it’s easier to create neologisms using hanja, similar in a way to what we tend do in French, which is just to take an English word, add a French ending and call it a day.
That’s very interesting, thanks all for your replies about this. I hadn’t thought about how learning the hanja might help with understanding roots of words.
I do this all the time with Japanese - even this evening it was helpful to know that danpatsu-shiki (hair cutting ceremony at the retirement of a sumo wrestler) comes from the Chinese characters 断髪式 (sever; hair; ceremony). As I already know those readings it makes the word much easier to remember.
I hadn’t realised there was a similar concept in Korean.
I’ve heard about hanja before being similar to kanji, but looking through these I’ve learned a lot of these from wanikani. I’m not studying Korean right now but it’s good to know that the meanings carry over some. I may eventually try Korean but probably only after I feel more confident in my Japanese and wouldn’t get as much interference.
About the readathon -
I’d say crash the party 
I’ll tag @taiyousea but I bet she’d be up for a multi-lingual readathon or come up with some other fun way to include you!
There was quite a discussion on theWK forum about that. For this one, a lot of people are reading from the day before the equinox all the way into the weekend following it, so if you join on WK, then join as it suits you! It’s pretty chilled out fun and there will probably be people posting all week.
Crashing the party would be fun actually. I feel like it’d be a good opportunity for me to do some Japanese reading (in the spirit of the original challenge), and finish a few Korean novels (maybe finally get the number of books I’m reading below 20?).
I didn’t want to join the wanikani challenge because it says explicitly that the point of it is to read more in Japanese (and for whatever reason I feel like the 100 or so kanjis I know and 0 grammar wouldn’t get me very far ) but hey I’ll still take it to heart and follow the rest of the rules!
I feel like I could still participate in WaniKani and just not add my results to the tally, but since I don’t even use the forums I would feel weird posting just the results in Korean… But for those of you active over there I feel like that might be an option to allow you to read in other languages (pending approval by taiyousea)
hooooow do you keep momentum?? i feel like if i go over 5 i have no time to make any significant progress in any of them, and reading feels that much slower.
TL;DR: acabé 2 libros, y compré otro.
이상한 과자 가게 전천당 1 | L21
siguiendo con los porcentajes de comprensión por semana del book club:
EN
this section it felt like i was looking up every other word, the 0 look-up passages were few and far between, BUT! fun word alert, 시간문제 means a question of time. it feels like when i found out password is 비밀번호.
나빌레라 2 | L19
끝!! libro acabado. leeré el siguiente? claro que sí.
숲속의 담 3 | L17
끝 también. los flashbacks entre capítulos me están confundiendo un poco, y la trama con 코나 también. Pero me gusta dónde está yendo la historia. on my way to tagging it as found family.
leeré el siguiente? see above.
EN
finished it as well. the flashbacks and the 코나 storyline are confusing me, but I like where this is going. will I read the next book? yes absolutely.
[라르고][BL] 아빠와 나와 가족이 되자 | L20
mmmmh, so I have thoughts. no encuentro el nombre del love interest, pero me está dando muchos red flags. para empezar, cuando se conocen y dice “no el niño no me interesa pero tú sí que eres mi estilo” ?? i feel like if someone is insinuating you are being inapropriate to their child your first response shouldn’t be to hit on them??
and then my dude is having a good cry about his dead wife and that guy just goes and kisses him?? what is happening. anyway back to spanish. no me gusta, no veo que tengan química, es todo muy de repente sin ningún buildup. no sé. seguiré leyendo, pero por ahora el chico ese está on thin ice.
EN
i can’t find the love interest’s name, but so far he seems like a walking red-flag. “i’m not interested in your child, but you’re absolutely my type” my dude what is wrong with you. i’ll just repeat what i said above, i feel like if someone is insinuating you are being inapropriate to their child your first response shouldn’t be to hit on them?? and then the first guy cries about his dead wife, and the first thing he can think of is to kiss him? read the room maybe? i’ll keep reading, but that guy is on thin ice.
우리가 함께 걷는 시간 | L19
acabo de comprar este libro, que por lo visto debería ser bastante similar a 좋은 날이야, 네가 옆에 있잖아 | L21??. más prosa! yay!
no lo subí aquí pero sí que hice mis hanjas ayer! y hoy también, sólo que hice la mitad de lo previsto. quizá haga el resto más tarde hoy, quizá no.
fun hanja of the day
there is nothing fun about this. i forget everything as i go. this is a “trust the process” situation.
I’m a mess, I get easily distracted by new books and then forget about the other books . And because I keep doing that, I’ve accumulated quite the pile. Tbh I’m already happy it’s below 30 right now, a few months ago I was above 35, that was getting embarrassingly high.
It doesn’t necessarily feel like I’m affected progress wise. Some books I’ll have started for months and then just finish them in a day or two. Some books I won’t put down at all, I’ll just read that and nothing else until I finish it. So it really depends, but overall, as long as I’m still finishing books, it’s easy to see the progress.
