The best way of getting vitamin C into the diet is by feeding at least one high vitamin C veg or herb a day, like a slice of (sweet) pepper of any colour daily, a sprig of coriander/cilantro, parsley, dill or mint, a floret of stalk chunk of broccoli or a 1 inch slice of spring greens. That will suffice to cover the vitamin C intake of a healthy piggy.
https://www.theguineapigforum.co.uk...or-a-balanced-general-guinea-pig-diet.116460/
If you wish you can additionally give vitamin C, but do NOT add it to the water, as you cannot control the intake (and piggies usually drink noticeably less), so it only goes to feed algae blooms. I would recommend to top up the diet with additional vitamin C whenever your piggies are ill or suffer from a lowered immune system.
https://www.theguineapigforum.co.uk...vitamin-c-overview-with-product-links.115404/
Please do not be tempted to go overboard with adding vitamin C, as long term overdosing especially of young guinea pigs can lead to them developing scurvy (vitamin C) deficiency symptoms later in life as soon as the level drops for some reason. Moderation, as in all things, is key.
Do you have just one or two guinea pigs? Generally, two piggies will be healthier as they constantly stimulate each other. The "I want what you have got" also makes much less prone to become very picky when it comes to eating.
