A matter of flow

[starypotter]

Hi everyone,
How do I know if I have enough flow in my tank? And if my fish are in a QT without much flow, just a HOB filter, should I have an acclimation period in the tank for them?

I have a 75 gallon reef ready tank. ('standard' 48x18x21) It has a dual loc line return but an undersized pump. I calculated head only from the sump to the bottom of the tank, not the top where it's returned. And even then I think I miscalculated so the flow coming out of that is very weak.

I also have 2 SunSun 530GPH wave makers in there but I've read that their GPH could vary greatly on them, I've got one more but frankly I'm not sure if they're even doing much. Even when I put my hand right in front of it it seems pretty weak at least to me I'm not exactly sure what a proper flow should 'feel' like when I've got my hand in the tank.

According to the 10x rule I should have somewhere around 750 GPH in the tank, but with my two powerheads (I don't even count the return lines because they're so weak) I should theoretically have more than 10x yet one of my shrimp shed and I watched the exoskeleton lazily drift through the water which makes me think there isn't enough flow. I only plan to keep LPS and Softies. I'm thinking I'll need to get another powerhead of some sort.

As for the fish, many of them are very small, I have a particular affection for clown gobies so I have 4 of them in QT, and two small clownfish that I'd worry about in terms of flow. Should I shut down my powerheads for a while when I first put them in, just leave the return running and let them find safe places, or should I keep everything normal so they don't find a safe place then realize it's got too much flow when everything is up and running? I'm leaning with the later and just adding the fish over very slowly so they each have time to find a safe space before the next goes in, adding them all from weakest to strongest.

 

[legionofdoon]

530 GPH sounds pretty weak as far as turning them off. The ocean even on s calm day has way higher flow so the fish will be fine they will find a calm spot near the structure if they are bothered by it. I have probably 1500+ GPH going from my return into a 40 breeder and the fish corals and inverts are fine I have Cardinals and clowns and it doesn't bother them at all. I would put all fish in the same time. Just because one might be weaker now it might not be the case when they establish a territory. Think damsels. Good luck.

 

[starypotter]

530 GPH sounds pretty weak as far as turning them off. The ocean even on s calm day has way higher flow so the fish will be fine they will find a calm spot near the structure if they are bothered by it. I have probably 1500+ GPH going from my return into a 40 breeder and the fish corals and inverts are fine I have Cardinals and clowns and it doesn't bother them at all. I would put all fish in the same time. Just because one might be weaker now it might not be the case when they establish a territory. Think damsels. Good luck.

I do have 2 of the 530GPH, theoretically putting me at 1060 plus my returns but they're so weak I won't include them in my calculations even. And I must say that I won't take too long between adding them, I was only thinking a half hour or hour between some of the little ones but that is something to consider especially since they're mostly getting along now.

 

[trido]

. In a tank you want to have 30-100x flow. The fish dont care what the flow is as long as they can get oxygen your corals are all that matter in that regard. For a good inexpensive pump, Id suggest saving up for an Icecap gyre 1k or 3k. If you think you don't have enough flow, you absolutely don't have enough flow. When you start thinking you have too much flow, then your in the ballpark of having enough flow.

 

[redfishbluefish]

The one thing you didn't mention are corals. If you have corals, you need a lot more flow. Check out Dana's MACNA talk, and specifically where he talks about flow, starting around 24:40 minutes.

 

[starypotter]

First of all, the 10x rule works for a sump. In a tank you want to have 30-100x flow. The fish dont care what the flow is as long as they can get oxygen your corals are all that matter in that regard. For a good inexpensive pump, Id suggest saving up for an Icecap gyre 1k or 3k. If you think you don't have enough flow, you absolutely don't have enough flow. When you start thinking you have too much flow, then your in the ballpark of having enough flow.

Ha that's a good rule to have! Glad to hear that my thoughts have been confirmed. I was thinking about a gyre or maybe an MP_. I must admit I do like the idea of being able to do the different lagoon, wave, etc modes but I'd like to not break the bank too badly.

The one thing you didn't mention are corals. If you have corals, you need a lot more flow. Check out Dana's MACNA talk, and specifically where he talks about flow, starting around 24:40 minutes.

I do have corals in there currently and they mostly seem to be doing very well. I have about 6 zoa frags, many of them seem to be growing but some seem to be only holding steady. I have some GSP that's growing like a weed as would be expected so not really the best indicator, and a hammer coral which has gown as well. All growth has been observed since only about the end of June when I got them. I also have some other LPS in QT now but they haven't even started their 76 days yet. An alveopora, a frogspawn, an galaxia, and two others likely a favia (?) and something yet to be identified but LFS said low light low flow.
Two mystery corals here.