Elegimos el prelavado y, ya de paso, el aclarado.

Because elegimos can be either:

• present tense: we choose
• preterite: we chose

For -ir verbs like elegir, the nosotros form is the same in both tenses.

So you tell them apart from context. In this sentence, it sounds like a completed action, so it is understood as we chose.

Compare:

• Hoy elegimos el programa más corto. = Today we choose the shortest program / Today we’re choosing...
• Ayer elegimos el prelavado. = Yesterday we chose the prewash

Here, the sentence naturally reads as a finished choice.

Ya de paso is a very common expression meaning something like:

• while we’re at it
• since we’re doing that anyway
• might as well

It adds the idea that the second action is included because it is convenient or natural to do it too.

So:

• Elegimos el prelavado y, ya de paso, el aclarado.

means something like:

• We chose the prewash and, while we were at it, the rinse too.

It is idiomatic, so it is better to learn it as a whole chunk rather than translating each word separately.

Because ya de paso is inserted as a kind of parenthetical comment. It interrupts the main structure of the sentence.

Main structure:

• Elegimos el prelavado y el aclarado.

Inserted comment:

• ya de paso

So the commas show that the speaker is adding an aside:

• Elegimos el prelavado y, ya de paso, el aclarado.

In English, this is similar to writing:

• We chose the prewash and, while we were at it, the rinse.

The commas are not absolutely always required in every context, but in a sentence like this they are very natural.

Spanish often repeats the article with each noun:

• el prelavado y el aclarado

This is very normal and often sounds clearer and more natural than using just one article.

In English, we can easily say:

• the prewash and rinse

But in Spanish, repeating the article is common, especially when the speaker sees them as two separate selected options.

You may sometimes see one article shared:

• el prelavado y aclarado

but el prelavado y el aclarado sounds more standard and explicit here.

These are washing-machine or laundry-cycle terms.

• prelavado = prewash
• aclarado = rinse or rinsing cycle

A few details:

• lavado = wash
• prelavado = wash before the main wash
• aclarado = rinsing with clean water to remove detergent

In everyday appliance language, aclarado refers to the rinse phase or rinse option.

Because Spanish, like English, can leave out repeated elements when they are understood.

Full version:

• Elegimos el prelavado y elegimos el aclarado.

But that sounds repetitive. So Spanish normally says:

• Elegimos el prelavado y el aclarado.

In this sentence, ya de paso is inserted in between, but the idea is still the same:

• Elegimos el prelavado y, ya de paso, el aclarado.

The verb elegimos applies to both nouns.

Yes. Elegir and escoger both mean to choose.

So you could say:

• Escogimos el prelavado y, ya de paso, el aclarado.

That said, elegir is extremely common in this kind of context, and elegimos sounds very natural.

A small nuance:

• elegir is often the more general and frequent verb
• escoger can sometimes sound slightly more like pick/select, though in many contexts they are interchangeable

Yes, both are masculine singular nouns, so they take el.

That is because they are nouns formed around actions/processes, and in Spanish many such nouns are masculine:

• el lavado
• el aclarado
• el secado
• el centrifugado

Likewise:

• el prelavado

So the article matches the gender of each noun.

Y means and, linking the two things chosen:

• el prelavado
• el aclarado

So the sentence structure is:

• We chose X and, while we were at it, Y.

Without y, the sentence would feel incomplete or unnatural because the speaker is explicitly joining two selected options.

It is widely understood across the Spanish-speaking world, and very common in Spain.

In Spain, it is especially frequent in everyday speech. A native speaker might use it very naturally in casual conversation:

• Voy al supermercado y, ya de paso, compro pan.
• I’m going to the supermarket and, while I’m at it, I’ll buy bread.

In Latin America, people also understand and use it, though depending on the country you may hear other similar expressions too.

Yes. Aclarado can be:

1. a noun: the rinse / rinsing cycle
2. a past participle of aclarar: rinsed, clarified, cleared up, depending on context

In this sentence, it is clearly a noun, because it comes after el:

• el aclarado

That article tells you it is functioning as a thing, not as part of a verb form.

Yes, that is grammatically correct, but it means something slightly different in tone.

• también = also / too
• ya de paso = while we’re at it / might as well

So:

• Elegimos el prelavado y también el aclarado.
  just says both were chosen.

But:

• Elegimos el prelavado y, ya de paso, el aclarado.
  suggests the second choice was added almost as an extra, because it made sense to include it.

So ya de paso adds more attitude and context than también.

In standard Spain Spanish, approximately:

• elegimos → eh-leh-HEE-mos
• aclarado → ah-klah-RAH-thoh in much of Spain

A couple of points:

• The stress in elegimos falls on -gi-
• The stress in aclarado falls on -ra-
• In much of Spain, z and soft c are pronounced with a th sound, but here aclarado has no z or soft c, so the important Spain feature is actually the clear dental d between vowels, often softer than in English
• Final -do in everyday speech can sometimes sound a bit relaxed, but learners should pronounce it clearly

If you are learning Spain Spanish, the rhythm matters more than making it sound perfect immediately.