Better PE without the Tunzes...what gives?

[Doubledown]

I have 2 6100s in my 180. I took both out last night for a full vinegar soak/cleaning. I came home this evening and every coral in my tank had better PE than they ever do with the streams running. I use a Dart for a return through 2 SeaSwirls and 2 static lines, so I probably only had about 2200 GPH running all day. I know that the extra current is important for gas exchange as well as food trasport/waste removal of these corals, but it was nice to see some fuzzy corals finally (it's been a long, tough 9 months).

What gives? Why would I get better PE without the extra flow? I have lowered the stream out put to 60% when "on" just to see if this gets the same response from the corals.

 

[zapata41]

sometimes if a coral is in too much flow then PE will be not that good. is the flow from the streams random or static

Tim

 

[madmac]

This would jus be my guess. I've read somewhere here before where Bomber says the polyp extension can also be for respiration, 'think of it as gag response'.... so with the streams disabled, there is less circulation, so the animal coral is trying to breath and they do so better with polyps out than in.

 

[lduncan]

The corals are trying to breathe.

With lower water flow, the boundary layer around the coral is larger, which means gas exchange proceeds at a slower rate. To try and compensate for this, the coral increases it's surface area to aid gas exchange.

With higher waterflow, the boundary layer is smaller, meaning that gas exchange can take place faster, so the coral has no need to extend it's polyps as much.

Like others have said polyp extension can be a difficult sign to interpret, as polyps have a variety of different functions. Polyp extension is not always "good".

Layton

 

[oligotrophic]

<a href=showthread.php?s=&postid=7784434#post7784434 target=_blank>Originally posted</a> by lduncan
The corals are trying to breathe.


Layton

I have also tried switching off the Tunzes during feeding. Great PE, but notice almost all Acros do not like it when flow is near to zero. The very thick branching ones would start sliming, as if stressed. Keeping the Tunzes on IMO is better.

My tank has 2 6100s, and I'm adding more

 

[lduncan]

I wasn't advocating leaving the streams off.

Personally I'd do the opposite, the more flow the better.

 

[oligotrophic]

<a href=showthread.php?s=&postid=7784612#post7784612 target=_blank>Originally posted</a> by lduncan
I wasn't advocating leaving the streams off.

Personally I'd do the opposite, the more flow the better.

sorry for the confusion Iduncan, in my 1st reply post I wanted to type "i concur that The corals are trying to breathe" but having typed so rapidly that thought just slipped my fingersss

 

[Doubledown]

Thanks all,

Flow pattern in the tank is completely random. The 2 streams are set for 60%/30% fluctuation and the return goes through 2 Seaswirls that do not match swing speed.

Is there such a thing then as too much flow? 2200 GPH for the return and 6000 GPH from the streams is 45x turnover in the 180. The tank is not fully grown in (actually pretty sparce really) so I don't have corals blocking one another.

I have several wild/aquacultured pieces and several tank raised frags. I know we can't come near the flow of the ocean, but do corals adapt to the flow patterns/amounts in our tanks?

 

[King-Kong]

there are people running 2x that amount of flow in their tanks; 45x is far from too much.

Currently at 62x and could still use more.