diff --git a/solanaceae/ngc_ft1/cubic.cpp b/solanaceae/ngc_ft1/cubic.cpp
index 2c5ccfd..b538802 100644
--- a/solanaceae/ngc_ft1/cubic.cpp
+++ b/solanaceae/ngc_ft1/cubic.cpp
@@ -8,7 +8,7 @@ float CUBIC::getCWnD(void) const {
 		(_window_max * (1. - BETA)) / SCALING_CONSTANT
 	);
 
-	const auto time_since_reduction = getTimeNow() - _time_point_reduction;
+	const double time_since_reduction = getTimeNow() - _time_point_reduction;
 
 	const double TK = time_since_reduction - K;
 
@@ -18,6 +18,7 @@ float CUBIC::getCWnD(void) const {
 		+ _window_max
 	;
 
+#if 0
 	std::cout
 		<< "K:" << K
 		<< " ts:" << time_since_reduction
@@ -26,34 +27,36 @@ float CUBIC::getCWnD(void) const {
 		<< " rtt:" << getCurrentDelay()
 		<< "\n"
 	;
+#endif
 
 	return std::max<float>(cwnd, 2.f * MAXIMUM_SEGMENT_SIZE);
 }
 
 void CUBIC::onCongestion(void) {
-	const auto current_cwnd = getCWnD();
-	_time_point_reduction = getTimeNow();
-	_window_max = current_cwnd;
+	if (getTimeNow() - _time_point_reduction >= getCurrentDelay()) {
+		const auto current_cwnd = getCWnD();
+		_time_point_reduction = getTimeNow();
+		_window_max = current_cwnd;
 
-	//std::cout << "CONGESTION!\n";
+		std::cout << "CONGESTION! cwnd:" << current_cwnd << "\n";
+	}
 }
 
 size_t CUBIC::canSend(void) {
-	const auto flow_space = FlowOnly::canSend();
+	const auto fspace_pkgs = FlowOnly::canSend();
 
-	if (flow_space == 0) {
-		return 0;
+	if (fspace_pkgs == 0u) {
+		return 0u;
 	}
 
-	const int64_t cspace = getCWnD() - _in_flight_bytes;
-	if (cspace < MAXIMUM_SEGMENT_DATA_SIZE) {
+	const int64_t cspace_bytes = getCWnD() - _in_flight_bytes;
+	if (cspace_bytes < MAXIMUM_SEGMENT_DATA_SIZE) {
 		return 0u;
 	}
 
 	// limit to whole packets
-	size_t space = std::ceil(cspace / MAXIMUM_SEGMENT_DATA_SIZE)
-		* MAXIMUM_SEGMENT_DATA_SIZE;
+	size_t cspace_pkgs = std::floor(cspace_bytes / MAXIMUM_SEGMENT_DATA_SIZE) * MAXIMUM_SEGMENT_DATA_SIZE;
 
-	return std::min(space, flow_space);
+	return std::min(cspace_pkgs, fspace_pkgs);
 }
 
diff --git a/solanaceae/ngc_ft1/flow_only.cpp b/solanaceae/ngc_ft1/flow_only.cpp
index cedaae1..5bbfe43 100644
--- a/solanaceae/ngc_ft1/flow_only.cpp
+++ b/solanaceae/ngc_ft1/flow_only.cpp
@@ -19,6 +19,8 @@ void FlowOnly::updateWindow(void) {
 
 	_fwnd = max_byterate_allowed * current_delay;
 	//_fwnd *= 1.3f; // try do balance conservative algo a bit, current_delay
+
+	_fwnd = std::max(_fwnd, 2.f * MAXIMUM_SEGMENT_DATA_SIZE);
 }
 
 size_t FlowOnly::canSend(void) {
@@ -35,7 +37,7 @@ size_t FlowOnly::canSend(void) {
 	}
 
 	// limit to whole packets
-	size_t space = std::ceil(fspace / MAXIMUM_SEGMENT_DATA_SIZE)
+	size_t space = std::floor(fspace / MAXIMUM_SEGMENT_DATA_SIZE)
 		* MAXIMUM_SEGMENT_DATA_SIZE;
 
 	return space;
@@ -85,7 +87,6 @@ void FlowOnly::onAck(std::vector<SeqIDType> seqs) {
 		if (it != _in_flight.end()) {
 			if (it != _in_flight.begin()) {
 				// not next expected seq -> skip detected
-				// TODO: congestion event
 
 				std::cout << "CONGESTION out of order\n";
 				onCongestion();
diff --git a/solanaceae/ngc_ft1/ngcft1.cpp b/solanaceae/ngc_ft1/ngcft1.cpp
index 409d18d..2e33308 100644
--- a/solanaceae/ngc_ft1/ngcft1.cpp
+++ b/solanaceae/ngc_ft1/ngcft1.cpp
@@ -563,7 +563,8 @@ bool NGCFT1::onEvent(const Events::NGCEXT_ft1_data& e) {
 	}
 
 	// send acks
-	std::vector<uint16_t> ack_seq_ids(transfer.rsb.ack_seq_ids.cbegin(), transfer.rsb.ack_seq_ids.cend());
+	// reverse, last seq is most recent
+	std::vector<uint16_t> ack_seq_ids(transfer.rsb.ack_seq_ids.crbegin(), transfer.rsb.ack_seq_ids.crend());
 	// TODO: check if this caps at max acks
 	if (!ack_seq_ids.empty()) {
 		// TODO: check return value
@@ -588,7 +589,7 @@ bool NGCFT1::onEvent(const Events::NGCEXT_ft1_data& e) {
 
 bool NGCFT1::onEvent(const Events::NGCEXT_ft1_data_ack& e) {
 #if !NDEBUG
-	std::cout << "NGCFT1: FT1_DATA_ACK\n";
+	//std::cout << "NGCFT1: FT1_DATA_ACK\n";
 #endif
 
 	if (!groups.count(e.group_number)) {
@@ -610,20 +611,17 @@ bool NGCFT1::onEvent(const Events::NGCEXT_ft1_data_ack& e) {
 		return true;
 	}
 
-	//if ((length - curser) % sizeof(uint16_t) != 0) {
-		//fprintf(stderr, "FT: data_ack with misaligned data\n");
-		//return;
-	//}
-
 	transfer.time_since_activity = 0.f;
 
-	std::vector<CCAI::SeqIDType> seqs;
-	for (const auto it : e.sequence_ids) {
-		// TODO: improve this o.o
-		seqs.push_back({e.transfer_id, it});
-		transfer.ssb.erase(it);
+	{
+		std::vector<CCAI::SeqIDType> seqs;
+		for (const auto it : e.sequence_ids) {
+			// TODO: improve this o.o
+			seqs.push_back({e.transfer_id, it});
+			transfer.ssb.erase(it);
+		}
+		peer.cca->onAck(std::move(seqs));
 	}
-	peer.cca->onAck(seqs);
 
 	// delete if all packets acked
 	if (transfer.file_size == transfer.file_size_current && transfer.ssb.size() == 0) {
@@ -635,6 +633,7 @@ bool NGCFT1::onEvent(const Events::NGCEXT_ft1_data_ack& e) {
 				e.transfer_id,
 			}
 		);
+		// TODO: check for FINISHING state
 		peer.send_transfers[e.transfer_id].reset();
 	}