diff --git a/image_analysis/IndexAndRefine.cpp b/image_analysis/IndexAndRefine.cpp
index 1762839be..b3a285854 100644
--- a/image_analysis/IndexAndRefine.cpp
+++ b/image_analysis/IndexAndRefine.cpp
@@ -212,10 +212,17 @@ IndexAndRefine::IndexingOutcome IndexAndRefine::DetermineLatticeAndSymmetry(Data
     // hypothesis against the file's geometry - which is why a centre once scored 42/60 as a trial and
     // 5/60 when the same value was given on the command line.
     const DiffractionGeometry geom = experiment.GetDiffractionGeometry();
+    // ffbidx fits a known cell with a trimmed score that already discounts the spots off the lattice, so
+    // the lean seed that rescues a de-novo search on a flooded frame buys it nothing - measured, a single
+    // call with every spot indexes the same frames and gives the merge more observations - while the
+    // escalation cost it up to three calls a frame.
+    const std::vector<size_t> seed_caps = experiment.GetIndexingAlgorithm() == IndexingAlgorithmEnum::FFBIDX
+            ? std::vector<size_t>{std::numeric_limits<size_t>::max()}
+            : std::vector<size_t>{30, 80, std::numeric_limits<size_t>::max()};
     if (frame_calls && frame_calls->lattice_found) {
         indexer_result = *frame_calls->lattice_found;
         any_executed = true;
-    } else for (size_t seed_cap : {size_t{30}, size_t{80}, std::numeric_limits<size_t>::max()}) {
+    } else for (size_t seed_cap : seed_caps) {
         std::vector<Coord> recip;
         recip.reserve(std::min<size_t>(seed_cap, msg.spots.size()));
         for (const auto &i: msg.spots) {