I was told that paste worming is not enough and horses should be tube wormed from time to time. Is this true? If so, how often should it be done?

Tube worming used to be done as a matter of coarse once a year.
The only way to tell if your current worming program is working is by having your vet do a fecal count.
However, Most horses today stay fairly worm free- Remember horses are never 100% clear as they are ground eaters, this is where everyone poops.
There are many options when considering wormers. Interval dewormers[pastes] are used throughout the year[frequency depends on variables,average 8 weeks]
Daily dewormers are found in the form of feed through supplements[pellets,powders] and will help prevent re-infestation . You must first worm with a paste or tube wormer that contains Praziquantel & Ivermectin.
The 5 most common ingredients found in wormers are Ivermectin,Pyrantel Pamoate, Fenbendazole, Oxibendazole, and Praziquantel. A rotational deworming schedule means that you medicate 6 times a year, rotating different ingredients[brand name not important] in an effort to eliminate as many worms/larvae from different species as possible.

In the old days tube deworming was the most effective.

But not today. The pastes are just as effective and the cost is considerably less. Besides the stuff that they would use in the tubing is just Ivermectin in a liquid form.

Here is the cost breakdown. Cost are based off of the area I live in

Tube of paste dewormer (depending on brand) $2.00-18.00 (if on sale of not)

Tubing a horse. Farm call or office call. $50-75
Sedation (if needed) $55-60 (since some horse don't like the tubing)
Tubing $40-50
Liquid dewormer $20

I think I will stick with the paste Especailly since you can get most of them on sale on line for under $5 a tube.

i agree paste is the best xx lol

I agree with what the first poster said - have your vet do a fecal egg count if you're not sure. That will determine if your paste dewormer rotation program has been working. You may be able to resolve the issues, if any, with a different type of paste. Or the vet can let you know if tubing is required.

If you do have your vet do a fecal count, and you have had your horse on a regular deworming program don't freak out when it shows that the horse has a small infestation. Even horses that are on a good deworming program will still show a small count since they are grazers they are constantly picking up and re-infecting themselves. I have been in the medical field for over 13 years and not once have we tubed a horse, it is really not necesary. Some of the old timers still do it but it is not better than using paste or a liquid.