Dont go by the information provided in that link, there's some misinformation in it.
I recommend Valbazen as Robin stated. Dose each bird 1/2ml orally using a syringe without a needle, then repeat again in 10 days. Mixing wormers in water isnt very effective. You dont know if a bird drank enough of the mixture to be effective, or if a bird drank it at all, and sick birds wont drink at all.
Valbazen (Albendazole) is a Benzimidazole. Benzimidazoles are poorly absorbed and mostly excreted. We eat the eggs after using Valbazen or Safeguard (Fenbendazole). I'm still here typing after all these years.
However, if you suspect that you or a family member might have a reaction to the minute residue in the eggs, by all means toss the eggs in the garbage for 14 days after the last dosing.
Here's how you worm all your birds:
Go out to the coop with your flashlight early in the morning while it's still dark. It'll be easy to snatch a bird off the roost and worm it. Have your syringe preloaded 1/2ml Valbazen. If you have a heavy bird, dose 3/4ml.
Snatch a bird off the roost and cradle her in your forearm. Use your finger and thumb to pull straight down on her wattles and her mouth will open.
Use your free hand to grab the preloaded syringe and quickly squirt the liquid in the hens mouth. IMMEDIATELY let go of the hens wattles so she can swallow the liquid on her own. If you dont immediately let go of the wattles, she could aspirate and then there would be big problems.
Then release her. Draw up another 1/2ml Valbazen, snatch another bird off the roost and repeat this procedure until they are all wormed.
I recommend that you practice this procedure, a 'dry run' so to speak to make it easier for you. Also, you can have someone hold the hen for you if you wish, but you would still have to pull the wattles straight down in order to dose her.
The key is always letting go of the wattles after dosing orally. Also, sometimes a hen will shake her head while grabbing the wattles, hang on and she will tire out, then you can administer it orally.
Keep in mind the reason why you want to worm birds early in the morning: Not only is it easier, your birds have not eaten since the evening before and will have empty guts. Your birds will be starving, so will the worms and they will be at their weakest. This will make the wormer more effective eliminating the worms.
In addition, Valbazen is a very safe wormer. It slowly kills worms over several days, preventing toxic dead worm overload.
Then wait 2 hours after worming before feeding your birds. After two hours, give your birds a little feed at a time, gradually increasing rations back to normal feeding throughout the day.
Remember, your birds will be starving. They will gorge feed possibly causing impacted crop or gizzard.
Then repeat worming again in 10-14 days to kill worms hatched from eggs missed during the initial worming. Wormers have no effect on worm eggs.
Your soil will be contaminated with worm eggs. Since birds constantly peck the soil, they pick up the eggs and swallow them, starting the worms lifecycle all over again. This is called the "Direct Lifecycle."
This is why I worm birds monthly, to end the worms lifecycle. Also penned birds are more susceptible for worm infections. This is why I have sand in my pens and coops. Sand keeps everything dry and deters insects.
Anyone who says a chicken can handle a small wormload doesnt know what they are talking about.
What's a small wormload? ONE female large roundworm lays thousands of eggs onto the soil each day to be picked up by the chickens. There is no immunity to worms. That's why we worms dogs and cats monthly, same for chickens.
What damage has been done internally by the time you see a worm when it's excreted? There are only two reasons why a worm is excreted: There isnt anymore room in the guts and was excreted. Or, it died of old age. Worms cannot survive outside the host. Intestinal wall damage has occurred preventing proper absorption of nutrients. They literally suck the life out of a bird.
Worms weaken birds by starvation, which makes birds susceptible to all kinds of diseases.
Capillary worms in particular are killers just by their sheer numbers.
Tapeworms are a different ball game and require praziquantel to kill them.
Valbazen takes care of all worms except tapeworms, same with Safeguard. However, Safeguard requires higher dosage and 5 days straight dosing each bird.
the-chicken-chick.com
www.valleyvet.com
www.jefferspet.com
www.purelypoultry.com
www.hobbyfarms.com
www.thegoodlifebackyard.com.au
www.wikihow.com
www.fresheggsdaily.blog
