# What determines water change intervals?



## blacksi (Nov 11, 2012)

I have had my tank running for 4 months now. It's a 75 gallon with a bio ball ( I know I know) filter. If I remember right I've got a 700 GPH powering it and another 400 gph powerhead in the tank with about 75lbs of live rock.

1 blue damsel 1"
1 purple dotty 1.5"
2 clown .75" and 1"
1 Hippo 1.25"
1 small 3 head Xenia
1 2 inch marble star fish
25 mixed snails
25 mixed crabs

I have only done 1 small water change (less than 5 gallons) to clean filter parts.

Everyone looks very healthy, and I only have small amounts of red and green algae.
I've got a protein skimmer I haven't figured out how to make work safely yet, it works but if I kill power and start it back up it floods so I have left it unplugged.

My water tests are near perfect as far as I can tell, so it seems like that if it tests good I can leave it be but not sure.


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## coralbandit (Jul 29, 2012)

As long as your nitrAtes are good{under 40,best under 20}(they look good)you don't really NEED to change water.With the inverts and coral you have you should also test kh and calcium regulary as any of those can ,and probably will change,becoming lower and deficient.If you don't have buffer for kh and calcium then changing water to boost levels is a option or get buffers to raise each(they are seperate buffers).I assuming your vials are ph,Ammonia,nitrIte and nitrAte?


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## blacksi (Nov 11, 2012)

Thanks for the quick reply, yeah those are the vials.

Ph, ammonia, nitrite nitrate. I have quit adding it lately but I added over a month or so 8 to 10 ounces of purple up because my Calcium was low. I am going to search what Kh is and I will probably be looking at get kits for those instead of relying on the occasional pet store visit to test. 

I didn't plan on corals but found that the small pieces can be pretty reasonable to experiment with so I figured I'd give it a try. I was also reading that the Xenia needs Iodine too. Is that a common test also, hope thats not Kh, lol.

Edit, it looks like KH helps the water to maintain stable PH levels. I didn't test mine but I know the first 2.5 months I had to add a PH buffer due to constant swings in PH and now it seems to have stabilized. So, hopefully that is a good sign.


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## coralbandit (Jul 29, 2012)

The pH and kH or associated in that if one is low the other usually is also,but in possibly different proportions.There are individual kH test kit(API)for about $9 and also calcium test kits. Both are easy to use.I haven't found a convient iodine test but the level necesary is very low.There are iodine supplements (by kent or many others) that could be added monthly or so in small amounts.


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## Reefing Madness (Aug 12, 2011)

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## blacksi (Nov 11, 2012)

Reefing Madness said:


> Ok ,so here is where it gets tricky, Purple up raises exsisting Calcium levels up. If your Calcium level is gone, then Purple Up will not raise anything. So its good to either do a water change, which I don't, or raise Calcium levels using a Calcium source. I use Calcion to raise Calcium up to par, and Purple up to raise dissolved levels back up when needed. Im getting tired of buyin both, I may just end up with the Calcion to use at all times.
> But, if your ALK, MAG, and CA are ok, and you dose to keep those levels up, no reason to do a water change. As long as your Trates stay under 40. Which, I don't get how your doing, especially without a Sump with Algae, and no skimmer. Are you feeding the fish you have?


LOL, yes I am feeding them twice a day. I alternate between brine and mysis and occasionally a few ciclid pellets just to get rid of them and add a little more variety. I slice the frozen cubes in 1/4's or 1\3's. I even break the rules and pinch some flakes in underwater to purposely feed my CUC. Their bellies are usually bulging after each feeding. Maybe it is because they are all so small?


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## blacksi (Nov 11, 2012)

Can you guys think of links for how to convert my Bio ball filter into anything more valuable?


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## Reefing Madness (Aug 12, 2011)

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## reddevillover (Sep 17, 2013)

Or, fill it with live rock. Honestly you don't even need the bio balls in there. The 75 lbs of Live rock should be good enough bio filtration.


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