Need advice on water changes

[luisht]

I have a biocube29 and I was wondering what do u guys recommend for water changes, how often, and what percentage?

[eklikewhoa]

Stocklist?

Percentage would depend on the stock, but weekly to bi-weekly, 20-80%

[BiGPiNK]

I do 25% weekly, but have a fairly high bio-load (4 fish, HUUUUGE CUC, 20 gals) This keeps all my levels at zero except for calcium, which is always about 100 points too low so i've started dosing liquid calcium every two weeks (alk is always 9 so 2 part is not correct in this instance, right??)
if i leave the water change for longer than a week, say by the second week, all inhabitants will show some signs that things aren't quite right, so i do it more regularly to ensure it never comes to that point.
The regularity you have to do water changes is pretty much dictated by how you want to treat your water, that is to say whether you want salt to be the only "additive" in your water, or whether you want to go down the route of dosing with a hundred different chemicals. i would say test your water, first decide what ranges you are happy with (for instance calcium levels should be between 280 and 350 ideally, so if you were comfortable within that range, but never want to drop below 280, then that is your, 'low' range)
when you test your water, if there's something amis, do a water change right then and there (your tank is cycled right?).
When you get a test in which all your levels are optimal, start testing again every 3-4 days, watching which levels remain constant and which levels begin to drop. keep testing until you start to approach your 'low' range, now would be a good time to do your water change. Hopefully the change will be enough to bring the dropping levels back up to scratch, if not, then you know your water change percentage should be increased, or you will have to start looking at additives for that particular level.
Trial and error is key at the end of the day, sometimes you get lucky and weekly changes will keep everything perfect, sometimes you just have to tweak things in terms of regularity or volume to get everything to become more stable.

Hope it helps.

[luisht]

Thank you for the advice BigPink, yes the tank is cycled. my stock list:
2 clowns
1 lawnmower blenny
1 firefish
3 astrea snails
2 hermits

Ive been doing 15% every 10 or 15 days