Yes you can combine two key phrases to create a unique domain. But just make sure that it will not be too long, or, if you have no choice, make a name that is easy to remember. Your example "swimmingpoolaccessories.com" is way too long but quite easy to remember.

You can still come up with other names. So yes, you can combine keywords/phrases to create a unique name. But I preferred to think of a short and easy-to-remember names so that users will not forget it easily.

If it is easy to remember, why would it be too long?

Are we talking about people typing it wrong here?

If i'm relying 90% on search traffic, does length matter?

Where traffic comes from search engine , remembering domain names does not work

We have one site Usedcarindelhi.com - which is keyword friendly

Can you pen down even 25 domain names in next 5 minutes which you have visited in last 1 week. You will see that you wont as it was search engine traffic

hi Gunzblazen

Yes! You can combined two keywords. to make a unique domain.
but make sure that when you are combining two keywords, that is not too long.

Because if you combined long key it display your keyword is too long.

I hope you understand my own explanation.

The amount of juice you get from keyword rich domains these days is virtually nothing, so you are better to go for a simple domain name or a brandable domain name.

The combination certainly is a good one however the length of the domain is compromised. It would be better if you choose either of them and add info or something of that sort as a suffix to keep it short. If you are willing to go with that long domain, its the best option for you (you get the dual benefits).